In 1942 Los Angeles fired 1,440 anti-aircraft rounds at nothing

At 2:25 a.m. on February 25, 1942 — less than three months after Pearl Harbor — air raid sirens sounded across Los Angeles County. A total blackout was ordered. At 3:16 a.m., the 37th Coast Artillery Brigade opened fire with .50-caliber machine guns and anti-aircraft shells. Over the next hour, they fired 1,440 rounds into the sky at what they believed were Japanese aircraft. The Battle of Los Angeles had begun.

There were no Japanese aircraft. The U.S. Coast Artillery Association later concluded that a weather balloon launched at 1:00 a.m. had "started all the shooting" and that "once the firing started, imagination created all kinds of targets in the sky and everyone joined in." Five civilians died — three in car crashes during the blackout, two from heart attacks.

Shell fragments damaged buildings and vehicles across the city. Secretary of the Navy Frank Knox called it "a false alarm." The Army suggested enemy agents might have flown commercial airplanes as psychological warfare. After the war, Japan confirmed it had flown no planes over Los Angeles.

A photo published in the Los Angeles Times showing searchlights converging on an apparent object later became a staple of UFO conspiracy theories — but the image had been heavily retouched before publication, standard practice for newspaper photography in 1942.