X3 to X54

The X- and XE-Class submarines were conceived during the Second World War: around 51ft (16m) long, they were designed to be towed by a 'mother' submarine and use their small size to complete stealth missions, such as attacking harbours and performing reconnaissance. Although they would not begin active service until 1942, the submarine crews achieved quite the record, racking up 167 honours betwee...