A D-Day rehearsal in which E-boat attacks and friendly fire killed at least 749 American servicemen, with the incident suppressed until after the war.
Key Facts
- American servicemen killed
- At least 749
- Date
- April 28, 1944
- Location
- Slapton Sands, Devon, England
- Attacker
- German Kriegsmarine E-boats
- Purpose
- Rehearsal for D-Day Normandy landings
- Secrecy
- Incident suppressed due to impending Normandy invasion
Location
Cause → Event → Consequence
Allied planners organized large-scale amphibious rehearsals in early 1944 to prepare troops for the Normandy landings. Exercise Tiger was staged at Slapton Sands in Devon, chosen for its resemblance to Utah Beach, but coordination and communication failures left the convoy vulnerable and created dangerous conditions during the live-fire phases of training.
On April 28, 1944, a convoy of LSTs participating in Exercise Tiger was intercepted by nine German E-boats in Lyme Bay. The attack, combined with friendly fire from the live-ammunition shore bombardment, resulted in the deaths of at least 749 American servicemen. Communication failures meant some vessels received no warning of the E-boat threat in time to take protective action.
Because the Normandy invasion was imminent, Allied commanders classified the disaster to prevent damage to morale and to protect operational secrecy. The incident was only minimally reported at the time and remained largely unknown to the public for decades after World War II ended.