Diesel-Electric submarines had been in use for years before WWI; there were many commissioned boats on both sides of the war before it even started, so there is no one particular submarine used in WWI.
However, the one boat that arguably had the most impact at the beginning of WWI was the German submarine U-20, which was responsible for sinking the British passenger liner RMS Lusitania. This single submarine attack had repercussions throughout the war, causing policy shifts in Germany considering submarine warfare, and which affected submarine warfare in general forever.
A submarine. Or in German, a "Unterseeboot" or U-boat.
the submarine
A U-boat was a submarine used by Germany in World War 1 and World War 2.
United States Submarine Operations in World War II has 577 pages.
submarine are important because it help alot of people doring world war 1.
underwater submarine
The Great War and it was also known as the War to End All Wars, However, after World War II, the Great War was renamed WW1.
World War 1
Underseaboat.
The Dumbo Ship
The first submarine wasn't invented in World War 1 but was invented in 1773 in the Revolutionary War by David Bushnell. It was called the Turtle.
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.
the German "U-Boat".
Below
USS Shark
The name U-boat was applied to German submarines.
A U-boat was a submarine used by Germany in World War 1 and World War 2.
United States Submarine Operations in World War II was created in 1949.
United States Submarine Operations in World War II has 577 pages.