The first Japanese attack on the U.S. mainland, in 1942, was triggered by cactus spines in the rear end of a Japanese naval captain.

In the late 1930s, Kozo Nishino was commander of a Japanese tanker taking on crude oil at the Ellwood oil field. On the way up the path from the beach to a formal ceremony welcoming him and his crew, Nishino slipped and fell into a prickly-pear cactus. Workers on a nearby oil rig broke into guffaws at the sight of the proud commander having cactus spines plucked from his posterior. Then and there, the humiliated Nishino swore to get even.

He had to wait for war between the U.S. and Japan, but on Feb. 23, 1942, he got his revenge. From 7:07 to 7:45 p.m., he directed the shelling of the Ellwood oil field from his submarine, the I-17. Though about 24 shells were fired from a 5.5-inch deck gun, little damage was done. One rig needed a $500 repair job after the shelling, and one man was wounded while trying to defuse an unexploded shell.

U.S. planes gave chase to the sub, but Nishino got away. Thereafter, American coastal defenses were improved, so the mainland suffered only one more submarine attack by the Japanese during the war, at Fort Stevens in Oregon.