During WW2, all the major countries involved used submarines.
U-boats
See website: Submarine
Submarines were not important during the Renaissance, as they were not developed until much later. The Renaissance period, roughly from the 14th to 17th century, was more focused on advancements in arts, culture, and science rather than naval technology. Submarines became significant much later, in the 19th and 20th centuries, when they offered new capabilities in maritime warfare, exploration, and research.
Germany
USSR
the submarine played a key part in world war 2 for many countries, Germany used them extensively against British shipping and to destroy royal navy ships, the British used them again to destroy a few well known German ships, Japan had submarines as well like the midget submarine they also used to attack the US, ad the united states also had submarines in the pacific theater.
A U-boat was a submarine used by Germany in World War 1 and World War 2.
Asdic
H. L. Hunley was the name of the Confederate submarine that was used during the American Civil War. It was the first combat submarine to successfully sink an enemy ship.
germany italy switzerland and more
The submarine was not developed during World War I. Submarines existed before the war, with the technology being pioneered by various inventors and navies. During World War I, submarines were utilized by different countries, including Germany with its U-boats, as a strategic naval weapon.