It's one of World War II's oddest, and least-known stories: In 1944 and 1945, the Japanese sent a fleet of hydrogen-filled, paper balloons across the jet stream to strike North America. And it worked.

Out of the 9,000 handmade incendiaries sent, 1,000 eventually landed here. And not just along the West Coast , but as far east as suburban Detroit.

Slate (via /.) reviews the tale, gives a warning or two about censorship, and provides a few links.

THERE'S MORE: "In my research for Terrors And Marvels: How Science
And Technology Changed The Character And Outcome Of World War II, I came across an original photo, in the FDR Library at Hyde Park, of one of the paper balloon bombs, tethered on a base in Montana," Defense Tech dad Tom Shachtman writes.

The photo was there because it had crossed the president's desk, and it had clearly alarmed him and his aides. (It is reproduced in the book.) In general the balloons did very little harm, though, no more than isolated lightning strikes might have done, and their landing sites were less predictable than lightning strikes.

The Canadian government did ready a plane full of peat moss that they could impregnate with bubonic plague, for retaliation on Japan in case one of the paper balloon bombs did contain biological, disease-causing agents. In withholding information on the balloons from the public until American and Canadian scientists could determine the make-up of the payloads, the censorship served its basic purposes: to prevent panic in the general public, and also to prevent trigger-happy people in the military from sending peat-bombs in return.