The men of the 12th Submarine Flotilla, as it was officially known, received their initial training for work in the X-craft submarines - which were little more than 50 feet long - on and around the island of Bute, in the Firth of Clyde.
They’re best known for the daring 1943 raid on the German battleship Tirpitz - a mission immortalised in the 1955 film Above Us The Waves, starring John Mills and Donald Sinden, and in numerous books since then.
Much less well known, though, is the crucial part those submariners played in a mission in the Far East which paved the way for the end of the war - and which led to the 18 men involved being showered with military honours.
The achievements of Operation Sable, Operation Foil and Operation Struggle were largely forgotten in the euphoria which followed the declaration of victory over Japan. And that’s a wrong which historian and author Dr Mark Felton has done his best to put right through the publication of his new book, The Sea Devils.
Dr Felton, whose previous book, Zero Night, is currently being developed into a Hollywood film, said his new work, as well as telling a “tremendously exciting” story, is a tribute the heroics of the 18 men who took part in those Far East operations - all of whom lived to tell the tale.
“Operation Source [the code name for the Tirpitz raid] is very well known,” he said. “But you come across some things when you’re researching other things, and I discovered a reference to two Victoria Crosses awarded as a result of action in the very last week of the war, relating to something called ‘Operation Struggle’ and the operations of XE Craft in the Far East.”
Those XE Craft were improved versions of the X Craft which had taken part in the Tirpitz raid. But their mission in the Far East was no less dangerous: the aim of Operation Struggle was to sink two Japanese cruisers anchored in the Strait of Johore, and in so doing to pave the way for Britain to take back Singapore by way of an invasion of Malaya.
“Winston Churchill was very keen that Britain should win back its colonies from Japan,” Dr Felton said, “and Singapore in particular was seen as the major prize.
“But the mission was incredibly risky. The operation took place more than 40 miles behind Japanese lines, and the channel was only 15 feet deep in some places.
“It was also the first ever attempt to have divers place limpet mines on an enemy vessell, and the divers faced a risk of oxygen narcosis after just 30 minutes’ work.
“Nor were these submarines particularly well developed in terms of being able to understand what was going on outside: when they surfaced, they basically surfaced blind. And on Operation Struggle, they took with them enormous two-ton charges. They were basically floating bombs.
“But the biggest threat was the Japanese themselves. Japan had recently executed a group of British and Australian commandoes in pretty horrible fashion, and the British forces in the Far East knew that if you were caught by the Japanese you would be tried and executed.
“It was one of the very few occasions British forces were issued with suicide pills.”
Operations Sable and Foil were even more vital; the crew of the two midget submarines involved were tasked with cutting deep-sea telephone cables linking Hong Kong with Saigon and Singapore, severing an essential Japanese communication link and paving the way for the atomic bomb attacks which would finally end the war.
Two crew members, Lieutenant Ian Fraser and Leading Seaman James Magennis, were awarded the Victoria Cross for their part in Operation Struggle, while eight more were also honoured. The most memorable aspect of all, though, was not the showering of medals on those involved, but the fact that all 18 men who took part in the raids lived to tell the tale.
“It was considered to be a virtual suicide mission,” Dr Felton said. “Each craft carried four or five men, but the submarines were only 50 feet long.
“You couldn’t stand up inside, and the missions lasted for 40 hours or more - in fact, the longest mission was over 80 hours.
“The air became increasingly stale, and the temperature climbed above 95F.
“But these guys really were a breed apart. Most of them were quite short - they had to be, given the size of the submarines they were working in. The Americans described them as ‘little guys with a lot of guts’.
“Some had been on the Tirpitz operation, so they knew what to expect. They were incredibly brave, but they were constantly in fear because the nature of the job was so dangerous.”
The risks in being a crew member on a midget submarine were obvious to anyone who knew anything about the Tirpitz raid. Six X-craft took part in that mission, and none returned home; nine lives were lost, with a further six crew being taken prisoner.
And in March of 1945 three crew members on an XE craft - the type used in the Far East operations - were killed in a training accident in Loch Striven, just yards from their Bute training base.
“The operations were far more successful than anyone expected,” Dr Felton said.
“Eighteen guys went in, and eighteen guys came back - unlike the Tirpitz raid, which suffered a high casualty rate.
“It really shows that we had perfected how to do things by this stage. And yet, while there have been several books on the Tirpitz operation over the years, and films such as Above Us The Waves, the operations in the Far East have been pretty much forgotten.
“The two Victoria Crosses were the last awarded for actions before the end of the war, and Victoria Crosses are not handed out lightly, but their efforts were overshadowed by the euphoria of VJ Day.
“However, it’s a tremendously exciting story, and it deserves to be told to a much wider audience.”