Although by appearance, The British Mark I & II "Manned" Torpedo (called "The Chariot", resembled a type of "Suicide" weapon. In truth, it was far from this idea. It's design was taken from a similar designed used by The Italians and their Commando Services. The Chariot was a controllable "mini"Submersible able to carry (and be controlled by) either 1 or 2 men. Controlled very much as a Torpedo in terms of a propeller turned Shaft, The Chariot was used by British "Frogmen" Commandos. One or two "Drivers" would straddle the weapon, submerging with Self Contained Underwater Breathing Apparatus (SCUBA).
The Mark I was the 1-man version, seen around 1943-1944. Of the 30 built, they weighed 1.5-tons and were 23-feet long. They were 3-feet wide and 3-feet tall. They could achieve 3-mph and remain at a depth of 75-feet for up to 5-hours. The Mark II was 30-feet long and weighed 5,600-pound. This was the "2-man" Version. A series of plates protected the steerage in front of each Driver.
In deployment, The Chariot would exploit an Enemy Harbor Entrance. Once inside, they could silently place a magnetic bomb (known as a "Limpet") - against the hull of the Target Ship. A timed fuse gave The Chariot crew time to escape. The Chariots were not all that effective.By 1944, only 1 "success" was recorded. Two Chariots such several Japanese Merchant Ships, in Thailand. Although the Project was halted, the theory of using a similar underwater covert/overt device would continue.