Military action
After barely a year of peace, the war was reignited by the Revanite Crisis.
EoD Lore: The Revanites engineered the Revanite Crisis and the attacks on Korriban and Tython to steal information they meant to use to restore Revan to life, and to create a new Infinite Army with which he would reunite the galaxy. While the Revanites were eventually stopped on Yavin 4, the truce was irrevocably broken.
The Empire offered to extend the truce indefinitely, and the Republic agreed to begin peace talks. Unfortunately, the offer turned out to be nothing more than a ruse allowing the Empire to begin a new offensive at a time and place of their choosing, destroying several major Republic bases along the Mid Rim.