Armies as diverse as the Red Army, Syrian Arab Army, and the Islamic State have turned their weapons against their own soldiers to force them to fight. There is little systematic evidence on how this fratricidal coercion affects battlefield performance. We argue that such practices generate compliance through fear, compelling soldiers with variable levels of resolve to conform to a uniform standard of battlefield behavior. First, coercion keeps some reluctant soldiers on the battlefield. This reduces rates of desertion, disappearances, and premature surrender, but increases deaths and injuries, as these reluctant warriors now find themselves in harm's way. Second, fratricidal coercion lowers the resolve of more committed soldiers, leading to lost battlefield initiative, and fewer acts of bravery. We test our claims using a mixed-method strategy, drawing on (1) monthly panel data on 1,048 Soviet Rifle Divisions in 1941--45, built from millions of declassified personnel files; (2) a paired comparison of two Rifle Divisions at the Battle of Leningrad (1941); and (3) 526 land battles (1939--2011) to assess generalizability. We find that fratricidal coercion reduces battlefield flight but increases casualties and suppresses initiative.