Along with the anniversary of the attack on Pearl Harbor, the beginning of December also marks the anniversary of an infamous World War 2 event in Wyoming.

On December 5, 1944, a Japanese balloon bomb landed just outside of Thermopolis, Wyoming. At around 6:15 p.m. that evening, four coal miners heard a whistling noise overhead, followed by an explosion that sent flames parachuting across the night sky.

The bomb was one of over 9,300 hydrogen Fu-Go balloons launched from Japan and is believed to be the first to land in the United States. Considered the world's first intercontinental weapon, the campaign was a failure. While several hundred balloons eventually made landfall, they did little damage and were responsible for only six casualties.

The Japanese Navy hoped the offensive would incite public panic. Instead, the United States War Department issued a censorship order prohibiting newspapers from reporting the mysterious balloons.

While the bomb in Thermopolis was the only documented explosion in Wyoming during War War II, other balloons may have landed in the state. Over the years, hundreds of fragments from Japanese balloon bombs have been discovered in remote areas of Alaska, California, Oregon, and Washington.

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