X-boats midget-submarines were used at D-Day by the British to ensure that their landings went well. The crews of the X-boats were made up of commandos from the elite Combined Operations Pilotage and Reconnaissance Parties, formed on the orders of Lord Louis Mountbatten. After the disaster that befell the Allies at Dieppe, everything was done to ensure success on June 6th 1944.
Five days before June 5th the original date for D-Day two X-boats sailed from Hayling Island, Hampshire. Each midget submarine had a crew of five men on board. It would be their task to guide in the British landing craft at Sword Beach. The fear was that the landing craft might drift towards rocks that skirted the specific landing points at Sword and it was the task on the submarine crews to ensure the landing craft stayed on course.
The space in each of the X-boats was extremely limited. Each submarine was just 51 feet in length and a maximum of 6 feet in width. The crew could not stand up once inside the X-boats. The crews took it in turns to have a four-hour sleep in the battery compartment of the X-boats and their diet was mainly tea and baked beans.
Once the crews had sailed to the beaches they simply had to lay in wait and vitally, ensure that they were not spotted by the Germans. If one had been spotted, it is quite possible that the game would have been up in terms of a surprise landing even if Hitler was convinced that the Allies would land in the Pays de Calais. The expertise of the crews was such that they watched unnoticed via periscope German soldiers playing football on Sword Beach just one day before the planned landings.
However, both submarines had to surface at 22.00 to listen to the BBC news broadcast at that time. While they were submerged neither crew could hear the news. It was vital that they did as a secret message was going to be broadcast on one of the bulletins that would tell them that the landings were on and that they had to be ready to do what was required of them.
During one of these broadcasts, the crews learnt that the landings were going to be delayed by a day. This put them in a quandary as they did not know if they had enough oxygen on board to last them. When it was felt possible to do so, the crews would surface to allow the men to have a quick walk about on deck and to take in some fresh air.
The 22.00 BBC news on June 5th informed both crews via a secret message that D-Day was about to start. They now knew that they had to be on duty at 04.00 on June 6th. They first knew the landings had started when a huge fleet of bombers flew above them to bomb German positions along the coastline. The two crews knew that it would not be much longer before the landing crafts arrived and it would their task to ensure they sailed on the right course to Sword Beach. The landing craft homed in on the lights that came from the two X-boats. Casualties at Sword Beach were minimal when the sheer magnitude of the raid is taken into account.