The deaths of five Americans killed in a U.S. airstrike in Afghanistan stand as a fresh reminder of the dangers of friendly fire, an element of war that is older than the nation.

In 1758, during the French and Indian War, a detachment of the British Army led by Col. George Washington got into a firefight with a fellow infantry unit that had arrived to offer assistance. At dusk on a foggy day, they apparently mistook each other for French forces, and at least 13 British troops were killed.

In the Civil War, Confederate Lt. Gen. Thomas "Stonewall" Jackson died of pneumonia eight days after being hit by friendly fire during the Battle of Chancellorsville in Virginia.