USS Tampa was one of six US Coast Guard cutters serving overseas on convoy duty during the war. Also serving were the cutters 'Seneca', 'Ossipee', 'Alconquin', 'Manning' and 'Yamacraw'. During TAMPA’s service in a foreign combat zone, she successfully escorted 18 convoys between Gibraltar and Great Britain all under the command of CAPT Charles Satterlee.
During the late afternoon of 26 September 1918, after escorting her 19th convoy safely from Gibraltar to Great Britain, Tampa, low on coal, detached and proceeded independently to Milford Haven, Wales. At 8:15 p.m. local time, the Imperial German Navy submarine UB-91 sighted Tampa and fired a single torpedo that hit and destroyed the cutter. The ship went down with all hands in less than three minutes, in the Bristol Channel.
When the warship sank, there were 130 people onboard, including 111 Coast Guardsmen, 4 US Navy sailors who were part of Tampa's crew, 10 Royal Navy personnel and 5 British Admiralty dockworkers who were aboard as passengers.
Alerted by the convoy flagship, whose radio operator reported having felt the shock of an underwater explosion, search and rescue efforts over the succeeding three days turned up only some wreckage, clearly identified as coming from Tampa, and a single unidentified body. Only an additional three bodies were later recovered, two from a beach near Lamphey, Wales, and the other at sea by a British patrol boat.