In military terminology, friendly fire or fratricide is an attack by belligerent or neutral forces on friendly troops while attempting to attack enemy/hostile targets. Examples include misidentifying the target as hostile, cross-fire while engaging an enemy, long range ranging errors or inaccuracy. Accidental fire not intended to attack enemy/hostile targets, and deliberate firing on one's own troops for disciplinary reasons, is not called friendly fire, and neither is unintentional harm to civilian or neutral targets, which is sometimes referred to as collateral damage. Training accidents and bloodless incidents also do not qualify as friendly fire in terms of casualty reporting.
An American B-17 Flying Fortress "Miss Donna Mae II" is damaged by bombs after drifting under the American bomber flying above it during the bombing of Berlin in 1944. The damage to the horizontal stabilizer caused the plane to go into an uncontrollable spin and crash, killing all 11 crew members.
Soldiers perform a night assault at Camp Atterbury Joint Maneuver Training Center during Bold Quest 2011, a combat assessment exercise to test the interoperability of target identification systems of different allied nations to reduce friendly fire incidents.
Fratricide is the act of killing one's own brother.
The Fratricide (1897) by Akseli Gallen-Kallela, illustrating the poem The Brother Murderer from Kanteletar