History Spotlight, 2/24

The infamous Battle of Los Angeles gets underway on February 24, 1942. Was it Japanese sub-launched planes? UFOs? "Dry-cleaning bags full of marsh gas?" Or just plain-old war hysteria? Nobody really knows for sure.
A little over two months after Pearl Harbor, the entire West Coast and most of the US was in the grip of war fever. Nobody really knew what the Japanese were capable of and the attack on Hawaii came as a giant shock. The characterization that the senior Montgomery Burns gives them on an episode of The Simpsons as a nation of "sandal-wearing goldfish tenders" wasn't that far off the mark from how Japan was viewed in the US in the 1930s. OK, so they beat the Russians soundly in 1904 and were riding roughshod over the Chinese peasantry, that didn't mean that they stood a chance against the proud men of the US military. It was traumatic when the Japanese military effortlessly decimated the US Navy at Pearl Harbor and threw the US Army out of the Philippines and other Pacific outposts.
The Japanese submarine I-17 that surfaced off the coast of Santa Barbara and shelled an oil refinery in the early morning hours of February 24 only fed the flames. When, later that evening, and on into the morning of February 25 radar operators saw hundreds of unidentified objects over the city of Los Angeles people could be excused for thinking this was the big one. The military ordered a city-wide blackout and begin firing thousands of 12 pound antiaircraft shells at them. The all clear was finally given at about 7 am on February 25. And that was it for the Battle of Los Angeles. The death toll was three civilians hit by falling shrapnel and three civilians who had heart attacks due to the stress. But what the heck were those things? Most of the possible solutions have glaring holes:
1) Japanese air raid. The Japanese weren't operating carriers off the coast of California (they barely had enough fuel to get to Pearl Harbor, 2500 miles west of LA). True, the Japanese had been experimenting extensively in using subs as aircraft carriers, but the experiments hadn't panned out. The I-17 carried a single reconnaissance seaplane in a hanger forward of the conning tower, but that wasn't anywhere near the thousands of planes that had been seen and the plane didn't go anywhere close to 300 mph.
2) Japanese fire balloons. Towards the end of the war, the Japanese launched several hot air balloons loaded with high explosive designed to be carried over the Pacific and detonate over US soil. These weren't in use until 1945.
3) Blimps. At the time, the US was the main supplier of helium in the world and, naturally, the Japanese weren't getting any of it. After the Hindenburg, people were very leery about filling lighter-than-air craft with hydrogen.
4) War hysteria and mass panic. The US Army takes a very dim view of the notion that several hundred of its members "lost their shit" over nothing and staunchly deny this explanation. I, however, take a very dim view of human nature and am never surprised by what people will do in a moment of crisis.
5) UFOs. 'Nuff said.

The military's final say on the matter is, basically, "We don't know and we don't want to know. It was probably planes or something." Odds are that, until the invention of time travel, nobody is really going to know what happened on February 24-25 over Los Angeles.