The Civil War was the deadliest war in American history. Altogether, over 600,000 died in the conflict, more than World War I and World War II combined. A soldier was 13 times more likely to die in the Civil War than in the Vietnam War. One reason why the Civil War was so lethal was the introduction of improved weaponry. Cone-shaped bullets replaced musket balls, and beginning in 1862, smooth-bore muskets were replaced with rifles with grooved barrels, which imparted spin on a bullet and allowed a soldier to hit a target a quarter of a mile away.