The Exercise Tiger Disaster An Uncovered Tragedy: On April 28, 1944, E-boats from Cherbourg attacked Exercise Tiger, a rehearsal for the D-Day landings, in Lyme Bay, England. High Casualties: The E-boat attack resulted in approximately 750 American servicemen losing their lives. A Cover-Up: The incident was so grave that US authorities ordered a complete information blackout to prevent the Germans from learning about the extent of the damage and future invasion plans. A Lasting Impact: Survivors