That time Los Angeles fought off an imaginary Japanese bombing raid

In February 1942, Army units defending Los Angeles launched a devastating barrage of anti-aircraft fire into the sky, sending up 1,433 rounds against targets reported across the city in the "Battle of L.A."

Fortunately for the occupants (but unfortunately for the egos of everyone involved), the City of Angels wasn't under attack.

In the months after the Pearl Harbor attacks, the American Navy was largely in retreat across the Pacific, and the West Coast was worried that it was the next target of a Japanese attack.

In reality, the chances of a Japanese attack on the West Coast were low since the Navy was pulling back from far flung outposts in order to secure ground they knew they had to hold, like California, Oregon, Washington, and vital bases on Pacific islands.

But LA was overtaken by fear and uncertainty in the early months of 1942. Then, on Feb. 23, a city in California was attacked by the Japanese. A long-range submarine surfaced near Santa Barbara, California, and shelled an oil refinery there.

The very next night, a light was spotted over the ocean off the coast, possibly a signal flare sent up to guide Japanese planes or carriers to their target. Then, a few hours later, blinking lights were spotted and an alert was called. When no attack materialized, the alert was called off.

But in the early hours of Feb. 25, radars picked up activity at approximately 12,000-feet. Lookouts reported dozens of aircraft closing on the city. "The Great Los Angeles Air Raid" was on, and the city residents and their Army gun crews knew exactly how to respond.

Army Air Force crews rushed from their beds to await launch orders and gun crews ran to their stations. Volunteer air wardens fanned across the city to enforce the blackout.

At 3:06 a.m., the first gun crews spotted their targets and began firing into the sky. For the next hour, a fierce barrage lit up the night as searchlights and shells looked for targets. In all, 1,433 rounds would be fired by gun crews.

Citizens drove through the street against orders and caused three auto fatalities while two others were lost to panic-induced heart failure. Fuzes failed to detonate some rounds in the air and they crashed back to earth where they destroyed property while luckily causing no fatalities.

But the embarrassing reality started to become clear at headquarters. With no reports of bomb damage and few reports of downed aircraft — none of which could be confirmed — either both sides were engaging in the least effective battle in the history of war or there were not actually any Japanese bombers.

The alert was suspended at 4:15 a.m. and later lifted entirely. Soon, the entire country heard that the reported attacks in Los Angeles were actually just a case of the jitters.

A 1983 military investigation of the incident found a possible explanation. A swarm of meteorological balloons had been released that night with small lights attached to aid in tracking. It's possible that the gun and radar crews saw these balloons and, in the nervous atmosphere, mistook it for an attack.