10 April 1942 - U123 sinks tanker Gulfamerica on its maiden voyage in a early morning blazing display 5 miles off Jacksonville Beach, Florida. The U boat commander used the bright lit resort town to light his target at 0422, that had stopped zig-zagging just 20 minutes prior. Kptlt. Reinhard Hardegen, the U boat commander purposely positioned his vessel carefully before finishing off the tanker to avoid errant shots that would endanger civilians ashore. Nineteen crewmen from the tanker perished. The Liberty Ship "Michael James Monohan" was named for one of the dead Gulfamerica victims. Mr. Hardegen survived the war, and returned to Jacksonville in 1990, where he was received as an honored guest. He would say of the occasion that "The town was very friendly to me."
Information from "Operation Drumbeat" by Michael Gannon, and Wikapedia.