The Battle of Cathar played a large part in changing the situation. During the Neo-Crusades that predated the invasion of the Republic, forces under the leadership of Cassus Fett, Mandalore's chief tactician, attacked the world of Cathar, enslaving and killing as many Cathar as possible. It was theorized later that this flagrant attack was one of many that were calculated to draw the Jedi into the conflict. The gamble paid off; after having revealed the truth about what really happened on Cathar, the young and charismatic Jedi Knight Revan—who became known as "The Revanchist"—[8] defied the Council and began to rally younger members of the Jedi Order, including his friend Alek, who began calling himself "Malak" during the wars, to his cause.[5] After lending their support to the battered Republic fleet, they soon proved to be more than capable commanders in the field, quickly rising through the ranks. Soon, they were given direct control over the entire Republic Navy. Revan used this newly-bestowed authority to spearhead the Republic war effort; under his inspired leadership, the all-but-defeated troops of the Republic recomposed themselves and began to push the Mandalorians back.[3] Some time during the Mandalorian Wars, Revan visited both Malachor V and Korriban, slipping closer to the dark side and alerting the Sith Emperor of the Sith Empire to his existence.[19]

After a series of bitterly-contested battles on Dxun and Althir, the war's climax was fast approaching.[4] As the fighting reached a fever pitch, Revan began to devise a way to end the war before the Republic was too weakened by the conflict to face the threat that was to come. Working in secret, he built a new Sith academy over the crumbling ruins of the older complex on Malachor V, and used the dark side energies contained within to bind the most trusted of his Force-sensitive followers to his will. These beings became the building blocks of the order of the Sith assassins—a group that he kept secret even from Malak.[6]

In 3960 BBY, Revan forced a final confrontation with the Mandalorians above Malachor V. During the battle, Revan lured Mandalore into a direct confrontation, facing and overcoming the Mandalorian leader in single combat.[4] However, Revan learned from the dying Mandalore that the Mandalorian Wars were arranged by the Sith, and that Mandalore had been manipulated.[20] After ending the Mandalorian Wars with a resounding, if very costly victory thanks to the activation of the Mass Shadow Generator by one of his Jedi generals, Revan and Malak led the remainder of their forces into the Unknown Regions under the pretense of tracking down the remnants of the Mandalorian fleet. As time went by without any word from the Jedi who had won the war for them, the Republic feared that they and the soldiers under them had been lost in some great, unknown disaster in the depths of unexplored space.[6]