The Mandalorians had returned to take revenge on the Republic and sate their lust for war and conquest. With the Jedi Council refusing to lend military aid‒believing the true threat was still unclear, and the risk of conflict-hardened Jedi falling to the darkness was high‒the Republic was unable to prevent the Mandalorians from devastating the planet Cathar. Millions died. This was the last straw for several young Jedi, who disobeyed the Council to join the war effort.
The most notable was Revan, a charismatic and skilled leader who rose to the rank of general. Revan's friend Alek, later known as Malak, distinguished himself on the front lines. Revan's tactics and Malak's unyielding strength turned the tide, helping the Republic forces to victory at Althir and Jaga's Cluster.
But the Council did not approve. Seeing their rash involvement in the war and their gradual adoption of Mandalorian tactics, the Council watched Revan and Malak's heroics uneasily, remembering the fall of Exar Kun.