In April 1944, Allied forces conducted Operation Tiger, a massive full-scale rehearsal for the Utah Beach invasion during D-Day. Taking place at Slapton Sands in Devon, England, the exercise was meant to simulate realistic combat conditions, complete with live naval bombardment. However, a series of catastrophic communication failures turned the dry run into a nightmare.
The core issue stemmed from a simple clerical error: the British Royal Navy and the American assault forces were assigned slightly different radio frequencies due to a typographical error in the official paperwork. Because of this misprint, British escort ships guarding the landing craft could not communicate with the American convoy, designated Convoy T-4, nor hear their distress calls. To make matters worse, one of the primary British escorts, HMS Scimitar, suffered a collision and returned to port for repairs without a timely replacement being dispatched.
Unprotected in Lyme Bay on the night of April 28, the slow-moving American Landing Ships, Tank (LSTs) became sitting ducks in the dark. Nine German E-boats on routine patrol intercepted radio chatter, spotted the convoy, and launched a devastating torpedo attack. Two LSTs were sunk and another was heavily damaged.
The assault, combined with friendly fire incidents during the landing practice, led to the deaths of 749 American servicemen—exceeding the actual casualty count suffered on Utah Beach during D-Day itself. Fearing a breach of operational security and a blow to troop morale, Allied commanders classified the entire incident under strict secrecy, leaving families in the dark for decades about the true fate of their loved ones.