The Sawston Village History Society's speaker in April was Ann Mitchell, whose father was killed taking part in the St. Nazaire raid without knowing that his wife was pregnant with her. She has clearly steeped herself in the story of the raid and of the men involved.
In 1942 the Germans had just commissioned the Tirpitz, and if it could safely get into the Atlantic would be able to wreak havoc on allied shipping. However, she would need to have a port with a large enough dock to which she could retreat for servicing. St. Nazaire was the only suitable port, which contained the Normandie dock which was large enough for the Tirpitz. If this could be taken out of commission, the Tirpitz would have to run the gauntlet of the English Channel to get back to Germany. Without St. Nazaire, the Tirpitz could not safely sail in the Atlantic, and in fact never did.
How to take out the Normandie dock was a problem for the British forces to solve. Bombing was just not accurate enough, and the Navy could not afford to sacrifice a front line ship. What they came up with was a combined navy and commando operation using HMS Campbeltown, which was an outdated ex-US navy ship built in 1919. She was stripped out and lightened to reduce her draught and modified to look something like a German destroyer, and packed with high explosive set in concrete. The plan was to crash her into the dock gates, open the seacocks so she sank and could not be moved, and set the explosives to go off after allowing time for the crew and commandoes to get off.
The plan was to sail from Falmouth accompanied by 18 motor launches carrying commandoes. As part of the operation, they would destroy machinery and other structures, and bring back the crew of Campbeltown. The fleet set sail on 25th March 1942, and were met by a British submarine marking the point where they had to turn into the Loire estuary, keeping out of the main channel. The date was critical to take advantage of high tides, but even so the Campbeltown grounded twice but was able to get herself off. St. Nazaire is 5 miles upriver, and to start off Campbeltown was flying a German flag and responded to signals from shore using the correct codes thanks to Bletchley Park. Eventually the Germans opened fire and it became very hot for the commandoes and crew, but they kept going and increased speed as they approached the Normandie dock gates. They crashed into the gates just 4 minutes late and stuck to them, opening seacocks to sink the stern. The demolition commando groups got off the ship and set about their work, as did the teams on the motor launches. The explosives went off at noon, the gates were destroyed and the dock was out of commission until 1947.
When it was time to get away, it was clear that most of the launches had been hit and were on fire so the planned retreat could not happen. The only thing to do was to try to fight their way through the town and try to make their way to Spain and Gibraltar. Most of them ran out of ammunition and had to give themselves up, but 5 did manage to get to Gibraltar and home.
Of the 611 men on the raid, 169 were killed, 215 were taken prisoner, 223 returned to England in the surviving motor launches, and five via Spain. There were 89 decorations awarded including five VCs, two posthumously. A monument was erected by the French in St Nazaire, who said that the raid was the first thing in the war which gave them hope. There is also a small monument in Falmouth.
If you found this talk interesting and you put St Nazaire raid into a Google search, you will find many articles on the subject, including an excellent programme by Jeremy Clarkson. Don't be put off by his motor-mouth reputation; it is completely absent.