By late April 1944, over one million men and women from 14 Allied countries were massed on the southern coast of Great Britain in preparation for Operation Overlord, the Invasion of France. Shipping requirements reigned supreme on Allied staffs and was by far the most important constraint to Allied operations. In May, the Allied General Staffs had to face the fact there simply wasn’t enough to go around and hard choices had to be made. Operation Neptune, the actual invasion of Normandy, was postponed to June. Operation Dragoon, the invasion of Southern France was postponed to August. All reinforcement to the Anzio lodgment in Italy was cancelled. And finally, all further landings in the Mediterranean were postponed indefinitely. This situation was primarily due to the shortages in two critical ship types: the small wooden LCVP, Landing Craft Vehicle Personnel aka “Higgins Boat”, and the large 4000 ton LST, or Landing Ship Tank, which could carry 300 troops and 30 vehicles. The LST had a draft shallow enough to disgorge its charges directly onto the beach. The LST was so important to Allied operations that an officer in Eisenhower’s headquarters was dedicated to knowing the status and location of every LST on the planet.
On 27 April 1944, the Allies were finishing up Exercise Tiger off the south coast of Great Britain. The previous morning, the sea sick soldiers of the 1st Engineer Brigade landed on the beaches of Slapton Sands, England which was painstakingly made to look like Utah beach, their invasion beach in France. It was a disaster. The British cruiser assigned to simulate the pre invasion bombardment actually caused real friendly fire casualties. And the chaos on and just off the beach needed no simulation, it was real also. That evening, the weary engineers loaded back up to do it again. The slow convoy took a long circuitous route to accurately simulate the travel time across the Channel to Normandy.
In Lyme Bay in the early morning hours of 28 April 1944, the convoy of 8 LSTs, escorted by a single small Royal Navy corvette, began its final approach to the beach. They never made it there. Nine German E-Boats, slightly larger versions of the famous American PT Boat, snuck out of their harbor at Cherbourg in Normandy to raid Allied ships in the Channel. They avoided Royal Navy and RAF patrols and minefields, and under cover of darkness, attacked the convoy. The E-Boats sank two LSTs and damaged two others before getting away unharmed. Over a thousand American soldiers and sailors died or were missing. Ten of the missing had clearances high enough that they knew the details of Operation Neptune, and Overlord was almost cancelled until their bodies were recovered and identified.
Unfortunately, the great loss of life was the least of the Allies’ problems. Adm Ramsay, who was only promoted to Eisenhower’s Chief of Naval Forces the day before, now only had the exact, and minimum, number of LSTs needed for the Normandy Landings. The loss of one more to any cause: enemy action, maintenance, accidents, whatever for any reason, would require Operation Neptune, and thereby Operation Overlord, to be delayed until July.