Exercise Tiger Disaster: 946 Die Rehearsing D-Day

Nine German E-boats tore into a convoy of American landing craft off Slapton Sands in Devon, England, in the early hours of April 28, 1944, killing 749 American soldiers and sailors in a D-Day rehearsal that became one of the war's most closely guarded secrets. Exercise Tiger was a full-scale practice landing for the Utah Beach assault, complete with live naval bombardment, and the convoy of eight LSTs (Landing Ship, Tank) was steaming through Lyme Bay with minimal escort when the German torpedo boats attacked. The disaster resulted from a cascade of failures. HMS Azalea, the sole escort corvette on station, had not received updated radio frequencies and could not communicate with the American LSTs. A second escort ship, HMS Scimitar, had been damaged in a collision and was in port for repairs without a replacement being assigned. The LSTs themselves were sailing in a straight line at a predictable speed, presenting easy targets. When torpedoes struck LST-507 and LST-531, the ships erupted in flames. LST-289 was hit but managed to limp to shore. Many of the dead drowned because they had been improperly instructed on how to wear their life preservers. Soldiers inflated the belts around their waists rather than under their arms, causing them to flip face-down in the water when they jumped overboard. The English Channel was cold enough to kill an unprotected swimmer within minutes, and rescue operations were slow and confused. Bodies washed ashore along the Devon coast for weeks. The US military classified the incident immediately. The dead were buried in temporary graves, and survivors were sworn to secrecy. The cover-up was driven by two concerns: protecting the secrecy of the D-Day plans, since the exercise replicated the actual Utah Beach assault plan, and accounting for ten officers involved in the exercise who held BIGOT-level clearance for the invasion details. Until all ten were confirmed dead or recovered, Eisenhower's staff feared the Germans might have captured someone who knew where and when the invasion would occur. All ten bodies were eventually found. D-Day proceeded six weeks later. The full story of Exercise Tiger was not publicly acknowledged until the 1980s.