In April 1944, the Allied High Command organized Operation Tiger, a large-scale live-fire rehearsal at Slapton Sands, Devon, to prepare American troops for the upcoming Normandy landings. Thousands of soldiers and sailors took part, practicing amphibious assaults with Landing Craft, Tank (LCT) and Landing Ships, Tank (LST). To ensure total realism and operational security, strict radio silence was enforced except on designated emergency networks.
However, a crucial administrative error doomed the convoy before it even reached the shore. The British Royal Navy headquarters responsible for escorting the convoy issued a revised radio frequency schedule to the American naval commanders. Due to a typographical error in the distributed orders, the British corvette HMS Azalea and the American LST convoys were tuned to completely different radio frequencies.
On the night of April 28, nine German E-boats on patrol in the English Channel intercepted the convoy. As the fast German torpedo boats attacked the slow-moving, heavily loaded American LSTs, frantic radio calls for help went totally unheard by the British warship escorting them. Tragically, over 700 American servicemen lost their lives in the surprise assault.
The disaster was immediately classified under strict wartime secrecy to maintain Allied morale and protect D-Day operational intelligence. The lessons learned from the fatal radio mix-up led to standardized Allied joint-command radio protocols, unified frequency distributions, and improved emergency signal procedures, directly saving lives during the actual Normandy invasion weeks later.