What is the earliest sailing submarine in the world?

The earliest submarine propelled by sails in the world was built by American robert fulton for the French government in 180 1.

Robert fulton's sail submarine is shaped like a cigar. It is more than 6 meters long. The ship's skeleton is made of iron and the shell plate is made of copper. When sailing on the water, sails are used to push it. When sailing underwater or when there is no wind, you can dive to a water depth of 89 meters by rotating the propeller at a speed of 2 nautical miles per hour by manpower.

Sail submarines carry mine weapons for underwater combat. It once carried 20( 1 lb ≈0.45 kg) pounds of mines to attack a small boat, but it did not achieve operational results, and the sail submarine did not get the attention of the French government. Later, with the support of Britain, Fulton built an underwater ship with water mines and attacked and sank a 200-ton Danish sailboat "doria". However, due to the change of the British government, Fulton's submarine was rejected by the Admiralty. Sail submarine disappeared on the stage of history.