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(Thursday, September 4, 1941, 12:45 p.m. UTC; during the Battle of the Atlantic, part of World War II) — The USS Greer, a Wickes-class destroyer in the United States Navy, became the first U.S. vessel fired on in World War II when a German submarine (later identified as U-652) aimed a few torpedoes at it today, sparking heightened tensions between Nazi Germany and the United States, three months before America officially entered World War II.

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The Greer was tracking the sub when a British bomber dropped depth charges on it, prompting the U-boat to fire on the destroyer.

Some two-and-a-half hours later, the Greer made underwater contact with a submarine, the Greer attacked immediately with depth charges. Neither vessel suffered any damage during the incident.

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The “Greer incident” would lead President Franklin D. Roosevelt to issue what became known as his “shoot-on-sight” order one week later on Sept. 11, 1941, effectively declaring naval war against Germany and Italy in the Battle of the Atlantic.