The Battle of Los Angeles, also known as The Great Los Angeles Air Raid, is the name given by contemporary sources to the rumored enemy attack and subsequent anti-aircraft artillery barrage which took place from late 24 February to early 25 February 1942 over Los Angeles, California.The incident occurred less than three months after the United States entered World War II as a result of the Japanese Imperial Navy's attack on Pearl Harbor, and one day after the bombardment of Ellwood on 23 February. Initially, the target of the aerial barrage was thought to be an attacking force from Japan, but speaking at a press conference shortly afterward, Secretary of the Navy Frank Knox called the incident a "false alarm." Newspapers of the time published a number of reports and speculations of a cover-up.
Some contemporary ufologists and conspiracy theorists have suggested the targets were extraterrestrial spacecraft. When documenting the incident in 1949, The United States Coast Artillery Association identified a meteorological balloon sent up at 1:00 am that "started all the shooting" and concluded that "once the firing started, imagination created all kinds of targets in the sky and everyone joined in". In 1983, the U.S. Office of Air Force History attributed the event to a case of "war nerves" triggered by a lost weather balloon and exacerbated by stray flares and shell bursts from adjoining batteries.