Crissom held a position as an officer within the Corellian Security Force throughout the Galactic War, a conflict that pitted the Galactic Republic against the newly emerged Sith Empire. While Corellia's war raged against the [Empire](/article/sith_empire_(post%e2%80%93great_hyperspace_war), Crissom fought alongside Hanley, Davit, and Officer Silas. Together, they launched an assault on Imperial troops who had seized control of the Corellian Security Force Academy situated in Axial Park. Before the Empire could overwhelm them, they received timely assistance and were saved by Republic troops.