Mercenaries

Introduction

Mercenaries, often referred to as the “world’s second-oldest profession,” have been part of the history of war since its beginnings. While their precise description has varied over time, generally speaking, mercenaries are fighters who are not members of the group that hires them (whether that group is a state, a city-state, or the followers of a feudal lord) and are usually motivated by financial gain (although this feature varies over time; the idea of motivation by financial gain makes little sense as a marker of a mercenary in the medieval period). This article focuses on mercenaries in the postclassical period, although there is an extensive literature on mercenaries in classical Greece and Rome. Moreover, the article focuses on mercenaries within the European tradition of war, as the use and impact of mercenaries are both extensive and distinct in the European context. Finally, this bibliography focuses specifically on the long lineage of entrepreneurial mercenaries (whether or not the entrepreneur was the leader of a band of mercenaries or a leader of a state selling mercenaries to another state). Other forms of foreign service, including permanent subsections of the state military relying on foreign recruits (such as the French Foreign Legion) and volunteers (such as those in the Spanish Civil War or mujahideen in Afghanistan) also exist but are beyond the scope of this article. Mercenaries have been hired by a variety of actors in order to supplement existing forces and/or to provide specific expertise in military tactics or technology. They have shifted from individual entrepreneurs able to sell their services to the highest bidder, either in groups or singly. This form of entrepreneurial mercenary was common roughly between the 12th and 16th centuries, and was gradually replaced by a more organized system, whereby states took control of the mercenary trade and bought and sold soldiers from one another, a system that began around the 15th century and ended after the Crimean War in the mid-19th century. In the 20th century, mercenaries reappeared during the wars of decolonization in Africa, again as entrepreneurial individuals, nearly always fighting against the interests of newly decolonized states. In the late 20th century, private military companies appeared in conflicts in Angola and Sierra Leone. These companies sold a broad range of military services, including providing combat troops. They have disappeared and been replaced by private security companies (PSCs), which again provide a variety of military and military support services stopping short of combat. PSCs appeared in large numbers during the conflicts in Iraq and Afghanistan. There has been surprisingly little written about mercenaries, particularly pre-20th-century mercenaries, as a category on their own, separate from studies about the overall organization of war in a given period. However, a number of these broader accounts of military organization are a good introduction to mercenary use, and they are featured throughout.

General Overviews

There are surprisingly few general overviews of mercenaries over a broad historical period. Most accounts focus on mercenaries in a particular era. Mockler 1969 provides a general history of mercenary activity from the medieval period through to mercenary involvement in the wars surrounding African decolonization, ending in the early 1970s. Mockler 1985 summarizes in great detail the pre-19th-century material in a chapter and examines the use of mercenaries in Africa, carrying the analysis through to the mid-1980s. Percy 2007 examines mercenaries from the 12th century through private security companies in 21st-century Iraq but does so with an explicitly international-relations focus, arguing that decisions to use private force have historically been influenced by a norm against mercenary use. France 2008, an edited collection, provides a very clear overview of medieval mercenaries, considering cases from a wide geographic spread and temporal period. Kiernan 1957 provides an in-depth examination of mercenaries in European armies, linking the use of foreign fighters to the development of absolute monarchy. Parrott 2012 examines the use of private enterprise to fight wars throughout early modern Europe, including during the Thirty Years War, arguing that the use of state-recruited and state-administered militaries is anomalous in European history. Thomson 1994 focuses on the use of force by private actors in general, considering mercenaries alongside privateers and mercantile companies. Her main concern is the manner in which the state monopolized the use of force externally by controlling these actors, having first achieved an internal monopoly on the use of force. Singer 2008 provides a very broad overview of the history of mercenary use and its evolution into the private military and security industry.

France, John, ed. Mercenaries and Paid Men: The Mercenary Identity in the Middle Ages; Proceedings of a Conference Held at University of Wales, Swansea, 7th–9th July 2005. Leiden, The Netherlands, and Boston: Brill, 2008.
DOI: 10.1163/ej.9789004164475.i-415Save Citation »Export Citation »E-mail Citation »
This edited collection extensively covers the medieval period, throughout Europe, from the 12th to the 16th centuries, with a notable geographical spread in the case studies (from Hungary to Ireland to Poland–Lithuania, among others). Also includes a discussion of the definition of a mercenary in this period. Excellent for wide coverage of the medieval period, but as the book consists of conference proceedings, some pieces are less polished than others.
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Kiernan, V. G. “Foreign Mercenaries and Absolute Monarchy.” Past & Present 11 (April 1957): 66–86.
DOI: 10.1093/past/11.1.66Save Citation »Export Citation »E-mail Citation »
Kiernan examines the use of foreign fighters in the armies of continental Europe, mainly focusing on the French as employers and examining the wide range of nationalities that were employed as mercenaries. Argues that mercenaries were essential in the transition from feudal states to absolute monarchies. Available online for purchase or by subscription.
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Mockler, Anthony. The Mercenaries. London: Macdonald, 1969.
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Begins with an analysis of medieval mercenaries and works through all main instances of mercenary use up until the early 1970s. Comprehensive and readable, it was for a long time the only book available on the history of mercenary use; it has been a main starting point for historical investigations into mercenaries. Its scholarly utility is diminished by an absence of referencing or a bibliography, making it impossible to analyze sources.
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Mockler, Anthony. The New Mercenaries. London: Sidgwick and Jackson, 1985.
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Mockler provides a brief history of mercenary use before focusing on mercenaries in Africa in the postdecolonization period. The book is still the definitive (if not the only) detailed source on this period and full of colorful anecdotes. Again, it suffers from an absence of referencing and documentation.
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Parrott, David. The Business of War: Military Enterprise and Military Revolution in Early Modern Europe. Cambridge, UK: Cambridge University Press, 2012.
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An excellent survey of how military organization relied on private provision across Europe, particularly useful in its comparative analysis of mercenaries in different countries. Has an unusual focus on the private provision of military support tasks, including the maintenance of armed men but also logistical supply chains, weapons and munitions, and even the building of fortresses.
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Percy, Sarah. Mercenaries: The History of a Norm in International Relations. Oxford: Oxford University Press, 2007.
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This book takes a long view of mercenary activity from the 12th century to the present use of private security companies. It operates from an explicitly international-relations academic standpoint, considering the question of how norms against mercenary use have influenced state decisions about when and whether to use mercenaries.
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Singer, Peter W. Corporate Warriors: The Rise of the Privatized Military Industry. 2d ed. Ithaca, NY, and London: Cornell University Press, 2008.
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The first sustained scholarly work on private military companies and private security companies. It contains a historical overview of mercenaries and is a good general introduction to the topic. The second addition adds a chapter to update the analysis to 2008, considering the war in Iraq, but as with any analysis of contemporary events the newer sections become quickly dated.
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Thomson, Janice E. Mercenaries, Pirates, and Sovereigns: State-Building and Extraterritorial Violence in Early Modern Europe. Princeton, NJ: Princeton University Press, 1994.
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Considers mercenaries alongside privateers and mercantile companies as private actors who wielded force outside state control. It focuses mainly on mercenary activity from the 15th to the 19th centuries and argues that the gradual monopolization of force in the hands of the state in the 19th century was responsible for the disappearance of mercenaries from European armies.
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Chronological and Geographical Analyses

The vast majority of the literature focuses on mercenaries in specific historical periods and places. The length of these sections reflects the historiography of the period. Generally speaking, the German military enterpriser system in the 15th and 16th centuries and the sale of mercenaries by the German states have attracted less scholarly attention.

English and French Mercenaries, 12th–16th Centuries

It is interesting how little has been specifically written about mercenaries during this period, as opposed to treating them more broadly as part of war. The main use of mercenaries during this period was during the Hundred Years War, so examinations of French and English military organization yield further insight into mercenary use. The exceptions are Fowler 2001 and Mallett 1999, which offer extended discussions specifically concerning mercenaries throughout this period. Fowler focuses on the mercenary companies of the Hundred Years War, their depredations, and attempts to control them. Mallett provides a first-rate survey of mercenary use throughout the medieval period. Other information about mercenaries can be gleaned from sources about military organization in general. Hollister 1965 explains how the feudal system necessitated the use of mercenaries, and Keen 1966 situates mercenary use in the context of just cause and just authority for war. Potter 1996 provides another examination of the extensive French use of mercenaries in the 16th century, contrasting it with the English experience, in the hotly contested European market for soldiers. Isaac 1999 enters into the debates about mercenaries in feudal society; these debates appear in many of these sources.

Fowler, Kenneth A. Medieval Mercenaries. Vol. 1, The Great Companies. Oxford: Blackwell, 2001.
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Fowler’s magisterial treatise on companies of mercenaries (routiers and écorcheurs) in 14th-century France, and efforts to control them by the papacy and the French state. Comprehensive and thoroughly researched, and an essential starting point to understand mercenaries during this period. Includes a useful primary source bibliography. It is supposed to have been the first of two volumes, but the second has not yet materialized.
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Hollister, C. Warren. The Military Organization of Norman England. Oxford: Clarendon, 1965.
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A useful book outlining military practices in Norman England, and explaining how mercenaries filled the gaps created by the feudal system.
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Isaac, Steven. “The Problem with Mercenaries.” In The Circle of War in the Middle Ages: Essays on Medieval Military and Naval History. Edited by Donald J. Kagay and L. J. Andrew Villalon, 101–110. Woodbridge, UK: Boydell, 1999.
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Highlights the considerable definitional difficulties associated with differentiating mercenaries in the feudal context.
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Keen, Maurice. The Laws of War in the Late Middle Ages. London: Routledge and Kegan Paul, 1966.
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Keen’s book is an essential overview of medieval warfare that considers mercenary use but also explains in some depth the notions of “just cause” and “just authority” and why routier (mercenary) captains were not considered to possess them.
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Mallett, Michael Edward. “Mercenaries.” In Medieval Warfare. Edited by Maurice Keen, 209–229. Oxford: Oxford University Press, 1999.
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A chapter of an edited volume on medieval warfare, it provides an excellent overview of mercenary activity throughout the medieval period. It explains the evolution of the distinction between “own” and “foreign” troops and the problems caused by mercenary depredation.
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Potter, David. “The International Mercenary Market in the Sixteenth Century: Anglo-French Competition in Germany, 1543–50.” English Historical Review 111 (1996): 24–58.
DOI: 10.1093/ehr/CXI.440.24Save Citation »Export Citation »E-mail Citation »
This article outlines the competition between England and France to recruit German mercenaries in the 16th century and argues that France had the advantage because of its larger experience with foreign recruitment. Available online for purchase or by subscription.
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Swiss Mercenaries, 13th–18th Centuries

Switzerland was a well-known source of mercenaries, with both companies and individual mercenaries appearing during the 13th century. By 1516, the Swiss had a permanent, treaty-based arrangement to provide troops for France. This arrangement ended only in 1793, a casualty of post-revolutionary turmoil. McCormack 1993 provides the only specific overview of Swiss mercenaries and is the obvious starting point for future research, but it is limited by its popular tone and absence of source material. Mockler 1969 (cited under General Overviews) surveys Swiss mercenaries extensively as part of his analysis of mercenary history, and Mallett 1999 provides further information in the context of an examination of medieval mercenaries. The Swiss theologian Huldrych Zwingli (b. 1464–d. 1531) was an ardent critic of the Swiss trade in mercenaries: Potter 1976 is a good source of his views.

Mallett, Michael Edward. “Mercenaries.” In Medieval Warfare. Edited by Maurice Keen, 209–229. Oxford: Oxford University Press, 1999.
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This excellent chapter in an edited volume on medieval war provides a clear picture of medieval mercenary use, with explanations of Swiss involvement and particularly of the expertise of Swiss pikemen.
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McCormack, John. One Million Mercenaries: Swiss Soldiers in the Armies of the World. London: Leo Cooper, 1993.
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The only book-length treatment of the history of Swiss mercenaries. A good starting point for further research, with very detailed accounts of Swiss mercenary action and the rise and decline of the trade, but without scholarly referencing and primary source material.
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Potter, G. R. Zwingli. Cambridge, UK: Cambridge University Press, 1976.
DOI: 10.1017/CBO9780511561290Save Citation »Export Citation »E-mail Citation »
This biography of Zwingli contains a useful discussion of his views of mercenaries.
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The Italian Condottieri System

The Italian system of condottiere (the word’s origins come from condotta, or contract) consisted of contracts between city-states and individual condottieri. Condottieri, or mercenary captains, raised bands to militarily assist their employers. Many mercenaries became famous, like Sir John Hawkwood (Giovanni d’Acuto) (b. c. 1320–d. 1394) and his White Company, and Erasmo da Narni (b. 1370–d. 1443), immortalized in a famous equestrian statue by Donatello (Donato di Niccolò) (b. 1386 or 1397–d. 1466). Niccolò Machiavelli (b. 1469–d. 1527) is perhaps the best-known opponent of mercenary use, and his criticisms stem from his observations of the Italian condottieri, and can be found in Machiavelli 1992 (first published in 1513). This era of mercenary history is perhaps the best covered, with Mallett 1974 and Bayley 1961 providing good overviews of the system and its workings. The effects of the condottieri system on Siena are examined in useful detail in Caferro 1998. Sir John Hawkwood has received specific attention, with Saunders 2004 providing an engaging and more literary portrait, while Caferro 2006 supplies scholarly detail.

Bayley, Charles Calvert. War and Society in Renaissance Florence: The De Militia of Leonardo Bruni. Toronto: University of Toronto Press, 1961.
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Bayley’s book focuses particularly on Florence’s use of condottieri (mercenary captains), with useful information about the condotta (contracts) themselves and financial arrangements.
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Caferro, William. Mercenary Companies and the Decline of Siena. Baltimore: Johns Hopkins University Press, 1998.
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This is a fascinating book arguing that the decline of Siena as an Italian power was caused by its relationship with mercenaries. Full of first-rate primary source material.
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Caferro, William. John Hawkwood: An English Mercenary in Fourteenth-Century Italy. Baltimore: Johns Hopkins University Press, 2006.
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A prize-winning account of the life of Sir John Hawkwood, full of Caferro’s unmatched archival research and detail about the system of condottieri (mercenary captains) and mercenaries more generally.
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Machiavelli, Niccolò. The Prince: A Revised Translation, Backgrounds, Interpretations, Marginalia. Edited and translated by Robert M. Adams. 2d ed. New York: Norton, 1992.
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First published in 1513. Machiavelli’s oft-quoted negative views of mercenaries are essential reading, and an important part of the picture of the republican dislike of mercenaries and preference for citizen military service.
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Mallett, Michael Edward. Mercenaries and Their Masters: Warfare in Renaissance Italy. London: Bodley Head, 1974.
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Mallett’s essential book considers Italian mercenaries from the 13th to the 15th centuries. Provides a clear picture of the evolution of the condottieri system and features an interesting rebuttal to Machiavelli, who almost certainly exaggerated his facts about mercenaries.
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Saunders, Frances Stonor. Hawkwood: The Diabolical Englishman. London: Faber & Faber, 2004.
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This book is an extremely engaging portrait of Sir John Hawkwood, linking him to the broader renaissance in interesting ways.
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Wallenstein and the German Enterpriser System

German military enterprisers, who were responsible not only for raising and outfitting regiments in the German states during the 15th, 16th, and 17th centuries but also for raising the capital for war, have received little scholarly attention in English. Redlich 1964 is a highly detailed two-volume account that remains the definitive starting point. There are two biographies of Albrecht von Wallenstein, the exemplar of an enterpriser: Mann 1976 and Mortimer 2010. Parrott 2012 (cited under General Overviews) considers the German enterpriser system in context of the wider European use of private enterprise during the Thirty Years War. Parrott argues that the military enterprise system during the Thirty Years War swung between two poles: one where the enterprisers were in complete control of their armies and effectively independent, and one where the state was the predominant military organizer but encouraged private involvement, with a wide range of activities between these two poles.

Mann, Golo. Wallenstein: His Life Narrated. Translated by Charles Kessler. New York: Holt, Rinehart and Winston, 1976.
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Mann’s immense biography of Wallenstein is a heavy-going read in this translation, which has also excised the voluminous notes and references from the original German, but is a good starting point for those who cannot access the original.
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Mortimer, Geoff. Wallenstein: The Enigma of the Thirty Years War. Basingstoke, UK: Palgrave Macmillan, 2010.
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A readable biography of Wallenstein that explains the workings of the military enterpriser system.
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Redlich, Fritz. The German Military Enterpriser and His Work Force: A Study in European Economic and Social History. Wiesbaden, Germany: Franz Steiner, 1964.
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This highly detailed, two-volume work is the definitive explanation of the military enterpriser system. It provides a clear explanation of how the system evolved and worked, and of Wallenstein’s career. Redlich also highlights the important differences between military enterprisers, who were responsible for raising capital and troops, and mercenaries, who were simply labor.
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Welsh, Scottish, and Irish Mercenaries in Continental Europe, 15th–17th Centuries

While the Swiss were one main source of mercenary personnel in the armies of continental Europe, the Welsh, Scottish, and Irish were another. Both the Swiss mercenaries and their British relations often came from poor areas with limited opportunities for young men, leading to their enrollment as fighters abroad. The almost constant state of war on the Continent from the mid-16th century until the end of the Thirty Years War meant that there was a significant demand for foreign manpower from the relatively peaceful “British” islands. Unlike the Swiss, the arrangements for Welsh, Scottish, and Irish mercenaries were not treaty based, and many enrolled in foreign armies on their own, although recruitment could and did rely on existing relationships between elites. In fact, the extensive foreign military service of Irish, Welsh, and particularly Scottish mercenaries in this period provides a fascinating angle from which to examine the trade, diplomatic, and aristocratic links between these nations and the Continent. Trim 2002 and Henry 1992 consider the period immediately before the Thirty Years War, with Henry examining how Irish military service played out in Spanish Habsburg territories, and Trim making an argument that many Scots were motivated to fight abroad via Protestant religious sympathies and delivered into service through aristocratic links. Understandably, the Thirty Years War, with its vast requirements in manpower, led to considerable recruitment of mercenaries and other private arrangements, including the German military enterpriser system outlined above. Worthington 2004 examines the links between military service and diplomacy created by Scottish military service abroad, while Ailes 2002 considers how foreign service led ultimately to migration and settlement of Scots in Sweden. Henry 1992 examines a similar phenomenon among the Irish in Spanish Flanders. Murdoch 2001 is a very useful edited collection that considers the whole historical span of Scottish foreign military service, while Hayes-McCoy 1937 examines Scottish mercenary service in Ireland. Conway 2009 examines what the author describes as the “twilight” of Scottish military service in the 18th century, in a piece that provides a nice transition into the gradual disappearance of mercenaries from European armies. The transition is discussed in the section on the 19th-Century Shift Away from Mercenary Use.

Ailes, Mary Elizabeth. Military Migration and State Formation: The British Military Community in Seventeenth-Century Sweden. Lincoln and London: University of Nebraska Press, 2002.
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Examines how foreign military service turned into permanent migration into 17th-century Sweden, with an unusual focus on officers rather than soldiers. Extends the history of British mercenaries in Sweden past the 1630s, when most accounts assume the practice ended during the English Civil War, and continues through to the 1660s and the advent of peace in Sweden.
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Conway, Stephen. “Scots, Britons and Europeans: Scottish Military Service, ca. 1739–1783.” Historical Research 82.215 (2009): 114–130.
DOI: 10.1111/j.1468-2281.2008.00458.xSave Citation »Export Citation »E-mail Citation »
Argues that Scottish soldiers, because of their history of foreign service, had a cosmopolitan outlook and saw British military service as one option among several other types of foreign service. Describes the beginning of the increasing recruitment difficulties that led to the shift away from mercenary use. Available online for purchase or by subscription.
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Hayes-McCoy, Gerard A. Scots Mercenary Forces in Ireland, (1565–1603). Dublin, UK, and London: Burns Oates and Washbourne, 1937.
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A detailed account of the history of Scottish mercenaries in Ireland more broadly as well as in the period specified. Very old-fashioned and somewhat cumbersome to read, but a strong starting point with a bibliography of primary sources.
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Henry, Gráinne. The Irish Military Community in Spanish Flanders, 1586–1621. Dublin, UK: Irish Academic Press, 1992.
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Examines the origins of Irish military service in Flanders, and the use of foreign military service by the crown to remove unemployed soldiers who might cause trouble at home. Also considers the resulting Irish émigré community, and its ties with the wider community of other exiles.
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Murdoch, Steve, ed. Scotland and the Thirty Years’ War, 1618–1648. Leiden, The Netherlands: Brill, 2001.
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This edited volume focuses on the broader Scottish contribution, including diplomatic, to the war. It also includes chapters examining Scottish service in various phases and locations of the war and in armies ranging from the Polish–Lithuanian, French, Dutch, and Swedish.
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Simpson, Grant G., ed. The Scottish Soldier Abroad, 1247–1967. Edinburgh: John Donald, 1992.
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A comprehensive edited volume considering every aspect of Scottish foreign military service, from medieval Ireland through to France (and French service in Scotland) and Russia.
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Stradling, R. A. The Spanish Monarchy and Irish Mercenaries: The Wild Geese in Spain, 1618–68. Dublin, UK: Irish Academic, 1994.
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Considers the role of Irish mercenaries with the Spanish Habsburgs, who were facing recruitment difficulties after the 1630s. The vacuum was easily filled by poor Irishmen, who were emigrating in large numbers. Considers religious and cultural links between Irish soldiers and their Spanish employers, links that the author describes as “umbilical.”
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Trim, David J. B. “Fighting ‘Jacob’s Wars’: The Employment of English and Welsh Mercenaries in the European Wars of Religion: France and the Netherlands, 1562–1610.” PhD diss., King’s College London, 2002.
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This excellent PhD thesis (available via the British Library) examines the recruitment of English and Welsh mercenaries in the European wars of religion that preceded the Thirty Years War. Trim argues that ties between Protestant aristocrats and complex systems of patronage facilitated the recruitment of mercenaries, who fought with Protestant ideals in mind. Challenges the view that mercenaries were always recruited from the dregs of society.
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Worthington, David. Scots in Habsburg Service, 1618–1648. Leiden, The Netherlands, and Boston: Brill, 2004.
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An examination of broader Scottish-Habsburg relations throughout the Thirty Years War, including diplomatic relations and migration. Worthington examines military service in both the Austrian and Spanish branches of the Habsburg Empire, using extensive primary source material. The book provides a useful map through an incredibly complex geopolitical space.
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British Mercenary Use, 18th–19th Centuries

The British reluctance to raise a standing army created significant recruitment problems, and by the 18th century these problems required the use of mercenaries to supplement British troops. British forces were accompanied by mercenaries during the American Revolution. Britain again faced difficulties during the lead-up to the Crimean War and recruited mercenaries, none of whom saw combat, because the war ended before they could be sent. Atwood 1980 examines the use of so-called Hessian mercenaries (actually from a number of German states) during the American Revolution. Percy 2007 (cited under General Overviews) examines the British decision to recruit mercenaries during the American Revolution and the Crimean War. Percy examines the parliamentary records to demonstrate that considerable opposition in the first case increased recruitment dramatically in the latter. Bayley 1977 provides an authoritative account of the British recruitment of mercenaries for the Crimea. Wilson 1996 examines the “supply” end of the mercenary trade and considers its importance in German states.

Atwood, Rodney. The Hessians: Mercenaries from Hessen-Kassel in the American Revolution. Cambridge, UK: Cambridge University Press, 1980.
DOI: 10.1017/CBO9780511523038Save Citation »Export Citation »E-mail Citation »
Atwood’s book provides perhaps the only in-depth account of the details of Britain’s recruitment from German states and the use of these mercenaries during the American Revolution.
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Bayley, Charles Calvert. Mercenaries for the Crimea: The German, Swiss, and Italian Legions in British Service, 1854–1856. Montreal: McGill-Queen’s University Press, 1977.
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Bayley’s fascinating book about the recruitment of mercenaries for the Crimea provides insight into Britain’s ongoing recruitment problems and the significance of the debates surrounding whether or not to hire mercenaries, a political conundrum that nearly brought down the government.
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Wilson, Peter H. “The German ‘Soldier Trade’ of the Seventeenth and Eighteenth Centuries: A Reassessment.” International History Review 18.4 (1996): 757–792.
DOI: 10.1080/07075332.1996.9640762Save Citation »Export Citation »E-mail Citation »
This article explains the mercenary trade from the perspective of the selling German states rather than the recipient buyer states. Wilson argues that the mercenary trade was as much about raising the international status of German princes as it was about financial gain. Available online for purchase or by subscription.
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The 19th-Century Shift Away from Mercenary Use

Britain’s recruitment of mercenaries for the Crimea in the 19th century was the last gasp of mercenary activity for a hundred years. When mercenaries reappeared, they were either used covertly or to undermine newly decolonized states—in other words, states still did not use them. There is interesting scholarship on why and how states were able to make such a definitive shift away from private force. Posen 1993, Thomson 1994 (cited under General Overviews), Avant 2000, and Percy 2007 (cited under General Overviews) all make different arguments about why states stopped using mercenaries in favor of citizens. Percy argues that the decision to abandon mercenaries in favor of citizen armies cannot be understood without reference to norms of patriotism and the antimercenary norm. The author uses France, Prussia, and Britain as case studies. Thomson argues that states stopped using mercenaries as part of a process that monopolized the external use of force in the hands of the state and, accordingly, mercenaries were abandoned alongside privateers and the authorization for mercantile companies to use force.

Avant, Deborah. “From Mercenary to Citizen Armies: Explaining Change in the Practice of War.” International Organization 54.1 (2000): 41–72.
DOI: 10.1162/002081800551118Save Citation »Export Citation »E-mail Citation »
In this excellent article, Avant argues that a combination of domestic factors, enlightenment ideals, and path dependency explains why states replaced mercenaries with citizens in their armies. Available online for purchase or by subscription.
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Posen, Barry R. “Nationalism, the Mass Army, and Military Power.” International Security 18 (1993): 80–124.
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Posen argues that the decision to abandon mercenaries and adopt a citizen army stemmed from changes in military structures and tactics (specifically, to a mass army relying on soldiers capable of independent action) and that once one state adopted a citizen army, other states were forced to follow or face military defeat. Available online for purchase or by subscription.
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Africa, Decolonization, and Entrepreneurial Mercenaries

After their long disappearance from the international stage, mercenaries reappeared in Africa during and after decolonization. There is a dearth of scholarly research on this period, and as such, it represents an opportunity for future work. The first use of mercenaries was in the Congo, where former colonial interests used foreign fighters to undermine the newly decolonized state. Mockler 1985 remains the most detailed account of mercenary action during this period, with extensive attention paid to each episode from the 1960s through to the mid-1980s. Unfortunately, nearly all subsequent accounts of the period rely either wholly or entirely on Mockler, who does not provide references for his research. The exceptions are included in this bibliography. Clarke 1968 provides a relatively contemporaneous account of mercenary activity in the Congo. Lockwood 1977 gives an account of the extraordinary trial of mercenaries captured in Angola in 1976. De St. Jorre 1972 tells the story of the Nigerian civil war and mercenary involvement in Biafra. “Mad” Mike Hoare, a mercenary captain, provides a colorful firsthand account of his exploits in the Congo (Hoare 1967). Weinberg 1994 provides a fascinating account of the many mercenary activities of Bob Denard (b. 1929–d. 2007), another leading mercenary leader. Burchett and Roebuck 1977 provides a general, if very slanted, history of the period. Roberts 2006 demonstrates that individual mercenaries are still challenging African states.

Burchett, Wilfrid, and Derek Roebuck. The Whores of War: Mercenaries Today. Harmondsworth, UK: Penguin, 1977.
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As the title suggests, this book is highly polemical, and its history of mercenary use in Africa is biased. However, it is worth examining to get a sense of the depth of feeling against mercenaries and also is one of the sources of the tendency to equate mercenaries and prostitutes.
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Clarke, Stephen John Gordon. The Congo Mercenary: A History and Analysis. Johannesburg: South African Institute of International Affairs, 1968.
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Written shortly after mercenary activities in the Congo, this book is a useful companion to Mockler.
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de St. Jorre, John. The Nigerian Civil War. London: Hodder and Stoughton, 1972.
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Journalist de St. Jorre provides a well-written account of the Nigerian civil war with useful details of mercenary involvement in Biafra.
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Hoare, Mike. Congo Mercenary. London: Hale, 1967.
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An engagingly written firsthand account of Hoare’s operations with five Commandos in the Congo. Obviously self-serving, but full of useful detail.
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Lockwood, George H. “Report on the Trial of Mercenaries: Luanda, Angola, June 1976.” Manitoba Law Journal 7 (1977): 183–202.
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A very interesting account of the 1976 trial of thirteen mercenaries captured during the Angolan civil war. Lockwood was part of a team of international observers sent to monitor the trial, which was widely viewed as highly politicized and resulted in the execution of two mercenaries. Available online for purchase or by subscription.
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Mockler, Anthony. The New Mercenaries. London: Sidgwick and Jackson, 1985.
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Still the only detailed account of mercenary activity throughout the decolonization period. Lacks references and a bibliography, but nonetheless packed with detail and colorful anecdotes.
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Roberts, Adam. The Wonga Coup. London: Profile Books, 2006.
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Roberts’s account of the 2004 coup attempt in Equatorial Guinea (led by ex-private military company, or PMC, employee Simon Mann) demonstrates that the sort of individual mercenary who caused African states concern in the decolonization period has not disappeared, despite the tendency to concentrate on PMCs and private security companies.
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Weinberg, Samantha. Last of the Pirates: The Search for Bob Denard. London: Jonathan Cape, 1994.
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Weinberg tells the fascinating story of Bob Denard, a mercenary so committed to his career that he crops up constantly throughout the period, including leading several coup attempts in the Comoros Islands.
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Private Military Companies

Mercenary activity was relatively sparse through the 1980s. However, during the early 1990s, two companies emerged offering military services including combat to governments in need. Executive Outcomes and Sandline were contracted to provide assistance to the governments of Angola, Sierra Leone, and Papua New Guinea. In all three cases, the contracts included training the armed forces as well as fighting against rebel movements. This new form of corporate mercenary attracted a considerable degree of attention but international disapproval, for combat services meant that the market for private military companies (PMCs) was very small and both companies went out of business. The works outlined in this section examine the appearance, organization, and implications of PMCs (Shearer 1998, Mills and Stremlau 1999, Cilliers and Mason 1999) as well as specific cases of PMC involvement in particular countries (Howe 1998, Dinnen 1999, Francis 1999). Howe 2001 considers African military organization as a whole and privatization in this context. Singer 2008 (cited under General Overviews) analyzes the involvement of PMCs in Africa and places them in context with the private security companies (PSCs) that followed in Afghanistan and Iraq.

Cilliers, Jakkie, and Peggy Mason, eds. Peace, Profit or Plunder? The Privatisation of Security in War-Torn African Societies. Johannesburg: Institute for Security Studies, 1999.
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An excellent edited volume containing many useful perspectives on private-military-company engagement in Africa, with a strong African focus. Includes chapters on the particularities of privatizing force in the African context, as well as case studies of Executive Outcomes and Sandline involvement.
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Dinnen, Sinclair. “Militaristic Solutions in a Weak State: Internal Security, Private Contractors, and Political Leadership in Papua New Guinea.” Contemporary Pacific 11.2 (1999): 279–303.
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This article provides an excellent summary of Sandline’s involvement in Papua New Guinea. One of the very few (if not the only) pieces solely directed at the Papua New Guinea case.
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Francis, David J. “Mercenary Intervention in Sierra Leone: Providing National Security or International Exploitation?” Third World Quarterly 20.2 (1999): 319–338.
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Francis’s article supplies a good explanation of Executive Outcomes’ and Sandline’s work in Sierra Leone, and makes some challenging points about how the economic arrangements used to hire them were disadvantageous for the countries involved. Available online for purchase or by subscription.
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Howe, Herbert M. “Private Security Forces and African Stability: The Case of Executive Outcomes.” Journal of Modern African Studies 36.2 (1998): 307–331.
DOI: 10.1017/S0022278X98002778Save Citation »Export Citation »E-mail Citation »
Howe examines the participation of Executive Outcomes (EO) in Angola and Sierra Leone. Excellent detail about what the company actually did, utilizing interviews as evidence (including interviews with EO’s leadership). Available online for purchase or by subscription.
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Howe, Herbert M. Ambiguous Order: Military Forces in African States. Boulder, CO: Lynne Rienner, 2001.
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Very helpful resource for understanding the context of African military forces. Howe argues that the impact of private military companies in Africa cannot be understood without understanding the troops that the private fighters are meant to augment.
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Mills, Greg, and John Stremlau, eds. The Privatisation of Security in Africa. Johannesburg: South African Institute of International Affairs, 1999.
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An edited collection containing theoretical, legal, and empirical analyses of private- military-company activity. The contributions are uniformly strong.
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Shearer, David. Private Armies and Military Intervention. London: Oxford University Press, 1998.
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Shearer provided much of the earliest (and best) analysis of private military company (PMC) activity. In this short monograph, he outlines PMC interventions and argues that PMCs ought not to be regarded with suspicion.
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Private Security Companies

Private security companies (PSCs) began to appear in the early 2000s, with a great many springing up during the war in Iraq in 2003. These companies grew out of increased enthusiasm for privatization, generally in the United States and the United Kingdom. Particularly in the United States, many logistical services had already been privatized and, faced with declining military budgets, broader military privatization seemed sensible. One in ten of the American personnel were PSC employees at the start of the Iraq war, and total estimates of contractor numbers range from 30,000 to 50,000. There is a debate on whether or not PSCs can be considered mercenaries, and the literature on the subject is now voluminous. Thus, this segment is restricted to broad overviews of the phenomenon. Singer 2008 (cited under General Overviews), Avant 2005, Dunigan 2011, Kinsey 2006, and Krahmann 2010 provide overviews of the development of the private security industry and its practices in various situations and in different national contexts. Singer provides the first overview of the history and evolution of the private security industry. As industry developments have been so fast moving, the book is now slightly out of date but is still useful for its attempts at classifying the industry and describing its evolution. Chesterman and Lehnhardt 2007 supplies explanations of the legal control of PSCs. Scahill 2008 and Pelton 2006 consider the involvement of the company Blackwater in the war in Iraq.

Avant, Deborah D. The Market for Force: The Consequences of Privatizing Security. Cambridge, UK: Cambridge University Press, 2005.
DOI: 10.1017/CBO9780511490866Save Citation »Export Citation »E-mail Citation »
This excellent book is still the best theoretical analysis of private security; it also provides a wealth of empirical detail. The book considers how privatizing force affects three facets of state control over force (functional, political, and social) in a variety of cases, including the often-neglected contracting relationship between private actors hiring private forces.
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Chesterman, Simon, and Chia Lehnhardt, eds. From Mercenaries to Market: The Rise and Regulation of Private Military Companies. Oxford: Oxford University Press, 2007.
DOI: 10.1093/acprof:oso/9780199228485.001.0001Save Citation »Export Citation »E-mail Citation »
A comprehensive edited volume covering the legal and regulatory questions surrounding private military and security companies.
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Dunigan, Molly. Victory for Hire: Private Security Companies’ Impact on Military Effectiveness. Stanford, CA: Stanford University Press, 2011.
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This interesting book considers how the use of private security affects military effectiveness. It is one of the few dispassionate book-length treatments on the actual impact of these forces on the contemporary battlefield.
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Kinsey, Christopher. Corporate Soldiers and International Security: The Rise of Private Security Companies. Abingdon, UK, and New York: Routledge, 2006.
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A detailed book outlining the evolution of the private security company (PSC) industry, with a focus on the United Kingdom. Particularly useful in explaining the role of British private military companies in Africa in the late 1990s and their evolution into PSCs operating in Iraq.
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Krahmann, Elke. States, Citizens and the Privatization of Security. Cambridge, UK: Cambridge University Press, 2010.
DOI: 10.1017/CBO9781139042727Save Citation »Export Citation »E-mail Citation »
Krahmann’s book is a thoughtful discussion of how the use of private force affects the social contract and the relationship between civilians and militaries, looking in depth at social contract theory and at three national case studies (the United Kingdom, the United States, and Germany).
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Pelton, Robert Young. Licensed to Kill: Hired Guns in the War on Terror. New York: Crown, 2006.
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Pelton’s entertaining and informative account of the role that private security companies play in Iraq is both useful and colorful. Pelton has unparalleled field experience in dangerous places, and the book demonstrates his inside knowledge, although the book is very much directed toward a popular audience.
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Scahill, Jeremy. Blackwater: The Rise of the World’s Most Powerful Mercenary Army. New York: Nation, 2008.
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First published in 2007, and perhaps the best-known book about private military companies in the broader popular market, it is essential reading because of how much it has been relied upon in the media. Scahill has been accused of a polemical style and of overestimating the number of contractors in Iraq. The book, however, provides useful information about Blackwater and also about the problematic contracting process in the United States.
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International Law

Mercenaries have been of interest to scholars of international law, as their use during the wars surrounding decolonization created a flurry of international lawmaking, most of which was ineffective. Many of these international legal discussions contain useful insights into the historical evolution of mercenaries, the process of international law making (in particular, the legal history of antimercenary law), and contemporary accounts of mercenary activity. Examining legal scholarship provides valuable historical insight into why states wanted to control mercenaries and what they found objectionable about mercenary activity. Great Britain Privy Council (Diplock and de Freitas 1976) is the British government’s official inquiry into mercenaries after British nationals were among the thirteen captured and convicted in Angola in 1976. Van Deventer 1976 outlines the process of creating Article 47 of Additional Protocol II, which defined a mercenary and specified that mercenaries should not receive prisoner-of-war status. Burmester 1978 provides a survey of the relevant legal instruments shortly after the creation of Article 47. Cassese 1980, Taulbee 1985, Kwakwa 1990, and Major 1992 analyze existing law and trace developments up to the time of the authors’ writing. Zarate 1998 is the first legal scholar to address the appearance of private military companies and consider whether or not antimercenary law can or ought to apply to them.

Burmester, S. “The Recruitment and Use of Mercenaries in Armed Conflict.” American Journal of International Law 72.1 (1978): 37–56.
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Burmester’s article provides a thorough survey of all the instruments that might be used to control mercenaries, including neutrality and foreign enlistment legislation and the positions of historical jurists like Francsico de Vitoria (c. 1483–1546) and Francisco Suarez (1548–1617). Available online for purchase or by subscription.
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Cassese, Antonio. “Mercenaries: Lawful Combatants or War Criminals?.” Zeitschrift für Ausländisches Öffentliches Recht und Völkerrecht 40 (1980): 1–30.
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The well-known international jurist and later president of the International Criminal Tribunal for Yugoslavia argues that antimercenary law is cynically created to reflect state interests and expresses his concerns about the provisions of Article 47 that would deny prisoner-of-war status to mercenaries.
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Diplock, Lord, Derek Walker-Smith, and Geoffrey de Freitas. Report of the Committee of Privy Counsellors Appointed to Inquire into the Recruitment of Mercenaries. London: Stationery Office, 1976.
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This report considers the problems caused by mercenaries recruited in the United Kingdom to fight in Angola. Its analysis of the problems of controlling mercenary activity and the difficulties of legally defining a mercenary remain as cogent now as they were in the 1970s.
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Kwakwa, Edward. “The Current Status of Mercenaries in Armed Conflict.” Hastings International and Comparative Law Review 14 (1990): 67–91.
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Very useful analysis of international law and the various UN resolutions from the General Assembly and Security Council dealing with mercenaries. Available online for purchase or by subscription.
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Major, Marie-France. “Mercenaries and International Law.” Georgia Journal of International and Comparative Law 22 (1992): 103–150.
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An exhaustively thorough analysis of international law with a useful potted history of mercenary use. The article is also interesting because of its timing (1992); the UN Convention was in force but private military companies had not yet appeared on the international stage. Thus, it is perhaps the most complete analysis of antimercenary law aside from private military companies and private security companies. Available online for purchase or by subscription.
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Taulbee, James Larry. “Myths, Mercenaries and Contemporary International Law.” California Western International Law Journal 15.2 (1985): 339–363.
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As well as an analysis of mercenary law, Taulbee’s article is a very interesting snapshot of the process of creating the UN Convention on Use, Training, Financing, and Recruitment. Written in 1985 (just past the midpoint of the lengthy process of creating the Convention), Taulbee’s article foresees what will go wrong with the Convention, which only came into force in 2001 and is widely regarded as useless.
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van Deventer, Henry. “Mercenaries at Geneva.” American Journal of International Law 70.4 (1976): 811–816.
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This article provides a useful summary of the mechanics of creating Article 47 and the legal debates about how to define a mercenary. Available online for purchase or by subscription.
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Zarate, Juan Carlos. “The Emergence of a New Dog of War: Private International Security Companies, International Law, and the New World Disorder.” Stanford Journal of International Law 34 (1998): 75–162.
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The first piece of legal scholarship to consider whether or not antimercenary law ought to apply to private military companies. Zarate provides a thorough history of lawmaking regarding mercenaries, as well as analyzing relevant law.
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Morality

The ethical and moral questions associated with mercenaries are particularly interesting, especially given the long history of moral objections to mercenaries and the new questions posed by the increasing use of private security companies in conflict. Machiavelli 1992 (cited under Italian Condottieri System) and Rousseau 1987 strongly criticize mercenary use. Machiavelli is probably the most-cited historical critic of mercenary use. His preference for citizen soldiers came out of a republican tradition that deemed military service an important civic responsibility. Many contemporary scholars have considered whether or not the use of mercenaries and private security companies can be morally justified. Percy 2007 (cited under General Overviews) sets out the nature of moral objections to mercenaries and traces their historical development and influence. Lynch and Walsh 2000 provides the first sustained examination of the subject. Baker 2008, Coady 2008, Pattison 2009, and Fabre 2010 consider how mercenaries can be understood in terms of just-war theory and enter into the most common moral debates about mercenaries. How do we define mercenaries? How does financial motivation make mercenaries morally suspect? Do mercenaries differ from soldiers who voluntarily enlist, perhaps for the money? Are mercenaries “whores of war,” and if so, does this matter ethically?

Baker, Deane-Peter. “Of ‘Mercenaries’ and Prostitutes: Can Private Warriors Be Ethical?” In Private Military and Security Companies: Ethics, Policies and Civil-Military Relations. Edited by Andrew Alexandra, Deane-Peter Baker, and Marina Caparini, 30–42. Abingdon, UK, and New York: Routledge, 2008.
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This chapter of an edited volume about private security companies points out that despite a common belief that mercenaries are unethical, little sustained philosophical work exists on the subject. Baker considers Machiavelli’s argument and probes the analogy between mercenaries and prostitutes.
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Coady, C. A. J. Morality and Political Violence. Cambridge, UK: Cambridge University Press, 2008.
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Coady considers the morality of mercenary use in chapter 10 of this book on political violence. He considers the problems with defining “mercenary” and the challenges of basing objections on financial motivation. He differentiates between mercenaries and private security companies on moral grounds.
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Fabre, Cécile. “In Defence of Mercenarism.” British Journal of Political Science 40.3 (2010): 539–559.
DOI: 10.1017/S0007123409990196Save Citation »Export Citation »E-mail Citation »
Fabre uses just-war theory to argue that there is nothing inherently morally objectionable about using private force (although current private security companies do not pass her test for the restrictions that would make the use of private force unobjectionable). Available online for purchase or by subscription.
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Lynch, Tony, and A. J. Walsh. “The Good Mercenary?” Journal of Political Philosophy 8.2 (2000): 133–153.
DOI: 10.1111/1467-9760.00096Save Citation »Export Citation »E-mail Citation »
In this seminal article, Lynch and Walsh consider the relationship between mercenarism and prostitution, as well as Machiavelli’s republican views and how the use of mercenaries affects state sovereignty. Available online for purchase or by subscription.
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Pattison, James. “Deeper Objections to the Privatisation of Military Force.” Journal of Political Philosophy 18 (2009): 425–447.
DOI: 10.1111/j.1467-9760.2009.00356.xSave Citation »Export Citation »E-mail Citation »
Pattison, while focusing mainly on the private security industry, considers “deeper objections”—in other words, moral objections that would persist even if private security companies were stringently regulated. These objections correlate with other moral objections to mercenaries. Available online for purchase or by subscription.
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Rousseau, Jean-Jacques. “A Discourse on Political Economy.” In Jean-Jacques Rousseau: The Basic Political Writings. Translated and edited by Donald A. Cress, 111–138. Indianapolis, IN: Hackett, 1987.
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First published in 1755. Like Machiavelli’s, Rousseau’s objections to mercenaries stem from the republican tradition. Rousseau (b. 1712–d. 1778) was particularly concerned that because merceanries were foreign they could be used to repress citizens.
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