The Statute of Westminster Act of 1931 was a parliamentary act passed by the British that said that the UK no longer had any power to interfere in a Dominion’s law-making process, where previously they had a veto. This meant that laws previously made by the British for a constituent Dominion were no longer a locked law.

This act can be seen as the primary enabler of de Valera’s Anglo-Irish relationship. Him and his own political venture of the time, Fianna Fáil, had been called a ‘slightly constitutional party’ by Seán Lemass. De Valera’s strategy for the next 12 years would be gradually strip away the symbolic and practical measures described in the Anglo-Irish Treaty which impeded independence for Ireland.
This started with the Oath of Allegiance. Although De Valera had entered the Dáil for the first time in 1927 and taken the Oath, calling it an ‘empty formula’, it was still problematic for him. It was a direct commitment to what he considered a foreign head of state, showing supremacy and allegiance. De Valera passed a bill removing the Oath, passing in the Dáil and being vetoed in the Senate. It soon came into law however. Churchill had rallied against this at the time it had been done, however the British political establishment had been in a period of general concession and appeasement and so it went generally uninterrupted.
The Senate which had opposed him was mainly made up of previous Cumann na Gaedheal establishment figures as well as prominent Protestants. It was an effective opposition to much of the Catholic and Gaelic-focused policy de Valera wanted and so in 1936 it was abolished in its design stipulated in the Treaty constitution. The Privy Council was a legal institution of the United Kingdom, which any Irish citizen could appeal to over the domestic judicial system, and have its verdict binding. At this time it was abolished, giving over full sovereignty to the Irish judicial system.

The Governor General was the King’s representative within Ireland as a Dominion, and the position-holder at the time was James MacNeill, Eoin MacNeill’s brother. De Valera disliked the Governor General as it was a symbol of British hegemony in Ireland. De Valera employed a strategy whereby he and his ministers would snub the Governor General by leaving whenever they had been put at a common function. De Valera wrote to King George V asking that MacNeill be dismissed saying that the King should always follow the advice of his ministers and MacNeill soon resigned to the pressure. De Valera installed Domhnall O’Buachalla, a shopkeeper, failed Fianna Fáil candidate and friend of de Valera into the position. He did not take office in the official residence of the Vice Regal lodge, instead staying in his home in Monkstown. De Valera only used him to sign legislation which was constitutionally required. This whole scheme was a ploy to reduce the importance and reverence of the position, which would implicitly reduce the symbolic power of the Dominion status and focus attention back on the Government leaders as leading a nationalist Ireland.

In the Abdication Crisis, a constitutional crisis occurred when Edward VIII stated his intention to marry a twice divorcée American commoner called Wallis Simpson. This was believed to be compatible in his position as head of the Church of England, and the British PM Stanley Baldwin offered his resignation. This was very relevant for de Valera’s premiership as he was a leader of a very Catholic Ireland which had uncontroversially banned divorce not long prior. The abdication crisis weakened Britain’s credibility and created a domestic political storm which strained attention elsewhere. De Valera used the situation in order to pass a new constitution, Bunreacht na hÉireann in 1938. This constitutional was extremely significant and it dismantled numerous terms of the Treaty Constitution. This included the making of Irish the national language in comparison to the previous co-equal status of Irish and English. It included an irredentist claim on Northern Ireland which created suspicion and distrust with the Northern Unionists who were already fearful, and antagonised the British. It created a republic in all but name, as it stipulated the President of Ireland as being the head of state and not the King. This can be seen as really the true end to Ireland’s effective lack of independence, as there was no longer any mechanism or uncontradicted symbolic link to Britain apart from the lack of a republic explicitly claimed. De Valera was under pressure from his friend, Bishop John Charles McQuaid to include a clause recognising the Catholic Church as the sole true church of Christianity. He understood the opposition he would encounter with this, and instead opted for a clause that said that the Irish state would acknowledge the Church as being in a ‘special position’ with the great majority. This served to confirm the Irish state as being a religious state, and expressly showed the influence the Church had. It affected Anglo-Irish relations by disconnecting the North which was expressly Protestant. De Valera made this worse by pronouncing that he was ‘a Catholic first, and politician second’, which is said to have enabled Craig to say the same thing in supporting institutional injustice against Catholic nationalists in the North.
When Fianna Fáil came to power in 1932, they did so on the back of a populist election campaign calling for an end to land annuities. These were payments Ireland had to make to the British regularly, and were seen with great opposition to many nationalists and republicans. Once de Valera came to power, he revoked the payments leading the British to apply tariffs on Irish cattle and dairy. De Valera responded by putting a 20% tariff on British industrial goods. The British believed that they could undermine de Valera’s popularity with the taxes, however public anger was directed towards them. The Economic War had hurt Ireland’s agricultural output hugely and had caused many people to immigrate to Britain. Ireland had been Britain’s second greatest trading partner at this time and so both sides desired a mutual compromise. The Cattle-Coal Pact of 1935 was a half-step towards this and essentially said that Britain agreed to buy more Irish cattle to the dismay of many British farmers, and Irish agreed to buy from coal from South Wales and Northern England, depressed regions of Britain which had not been economically competitive with Germany and Belgium.

An official end to this came with the 1938 Anglo-Irish Agreement. This ended land annuities with a single 10 million pound payment from the Irish side. It also ceded the Treaty ports of Berehaven, Lough Swilly, and Queenstown back to Ireland, which greatly angered Churchill who believed they were necessary to secure British military control. However, the British political establishment had been in a way of appeasement, and was also trying to court favour with the Americans with positive diplomatic endeavours. It is also understood to be a mutually beneficial pact in terms of both sides’ defensive interests at the time.
The cession of the Treaty ports was especially significant as it allowed Ireland to remain neutral in World War I. Neutrality was chosen for a number of reasons on the Irish side. The IRA paramilitaries still existed, and many of them wanted to co-ordinate with Nazi Germany as a mutual enemy of Britain. If Ireland joined the war, this could enflame their activity undermining state security. The Dáil was largely in favour of it, only James Dillion wanting to enter the war. De Valera also knew that neutrality, splitting from Britain’s interests was unquestionable proof of independence. However, this was ‘benevolent neutrality’ which clearly favoured the Allied side. German pilots were interned in the Curragh, while British pilots were delivered over the border. Airspace over Donegal was also granted by de Valera and there was some clandestine co-operation with military intelligence. De Valera had good working relationships with John Maffey, the British Dominion Secretary, and Eduord Hempel, the German ambassador. Hempel understood that Ireland was under pressure to be sympathetic to British interests due to geography, and so relayed to Germany against ‘Operation Green’. Still, the bombing of the North Strand by German air pilots is considered by some historians to be an intentional warning by Hitler to ease of abetting Britain, despite the compensation given. Britain had provisions for an invasion of Ireland but did not act upon them because Ireland had been an important source of food, any many emigrated Irish workers had worked in the army and in their industry, and they did not want to upset them.

Churchill asked for the Treaty ports, which was refused. He later made a vague offer twice to de Valera suggesting that he would be willing to offer unification if Ireland joined the war. This was refused as de Valera questioned Churchill’s ability to deliver this given the power the Unionists had. Due to Ireland’s refusal to shut off diplomatic connections with the Axis powers, the Allies blocked off all communication of war plans with them out of fear of co-operation between the two. Later, after the war had ended, Churchill spoke of Ireland suggesting that they had been aiding or allowing the Japanese and Germans to run amok. De Valera in a radio broadcast appealed for sympathy talking about a ‘nation that stood alone for 700 years’ and did not lose its national tradition. De Valera had personified Ireland in the war years, and neutrality did demonstrate on an international level that Ireland was independent.

De Valera successfully took steps to mean that the 26 county republic was in all practical aspects an independent state by gradually and strategically stripping away elements of subordination stipulated in the Treaty constitution. However, it can be said that he is responsible for copper-fastening partition with his focus on Gaelic and Catholic Ireland ignoring Unionist concerns.