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.

Jon Krakauer is an American writer and mountaineer. He is the author of bestselling non-fiction books—Into the Wild; Into Thin Air; Under the Banner of Heaven; and Where Men Win Glory: The Odyssey of Pat Tillman—as well as numerous magazine articles. He was a member of an ill-fated expedition to summit Mount Everest in 1996, one of the deadliest disasters in the history of climbing Everest.