disbanded on 17 September 1940. The warship, however, continued to operate in the Gulf of Mexico and Caribbean Sea out of her home port at Panama. After the United States entered World War II, Tattnall began escorting coastwise convoys in her area of operations, frequently through the Windward Passage between Cuba and Hispaniola, a dangerous area during the height of the Caribbean U-boat blitz. Though she made many sonar contacts and depth charge attacks, Tattnall registered no confirmed kills. Early in July 1943, the destroyer escorted her last Caribbean convoy north from the Windward Passage to Charleston, South Carolina. She arrived on the 10th, began conversion to a high-speed transport at the navy yard, and was redesignated APD-19 on 24 July. On 6 September 1943, the day following the 25th anniversary of her launching, Tattnall completed conversion. She finished her shakedown cruise in mid-September. Following post-shakedown repairs and alterations in late September, the high-speed transport began amphibious training—first, at Cove Point, Maryland, and later, at Fort Pierce, Florida. In April 1944, Tattnall was designated flagship of Transport Division (TransDiv) 13, the only high-speed transport division in the Atlantic theater. On 13 April, she departed the U.S. East Coast for Oran, Algeria, in company with , , , and . TransDiv 13 joined the 8th Fleet at the end of April, and Tattnall moved to Corsica to practice for her first assignment, the capture of Elba and Pianosa Islands in the Tyrrhenian Sea. However, before the invasion and during her training period, Tattnall was called upon to feign a landing near Civitavecchia, Italy, north of Rome, to draw off German reinforcements headed south to turn back the American forces breaking through at Monte Cassino and heading for Rome. The ruse apparently worked. The reinforcements never reached Monte Cassino; and, on the following day, German radio announced an Allied invasion north of Rome. On 17 June, the invasion troops went ashore on Elba and Pianosa. Tattnalls boats came under machine gun fire, but suffered no serious damage. After the landings in the Tyrrhenian Sea, the high-speed transport began convoy duty between Italian, Sicilian, and North African ports. Following that duty, she resumed amphibious operations, this time with members of the American-Canadian 1st Special Service Force embarked. Their mission was to capture the heavily fortified Hyeres Islands, located just east of Toulon, and hold them during the main landings in the invasion of