The most successful submarine of WW1 was the SM U-35 Type U 31 U-boat. It sunk 224 ships, not 223.
Sinking civilian ships without warning (un-restricted submarine warfare).
Primarily over 2,000 merchant vessels, with a sprinkling of allied warships.
Germany attempting to from a military alliance with Mexico
United States Submarine Operations in World War II was created in 1949.
unrestricted submarine warfare
The Uboat was a submarine made by the Germans
In World WarII, the germans named it a uboat
German Uboat torpedos sinking half of the Merchant Marine fleet
1. Unrestricted Submarine Warfare 2. Sinking of several US ships
Sinking w/o warning (un-restricted submarine warfare).
Sinking civilian ships without warning (un-restricted submarine warfare).
inability to remain neutralGerman submarine warfare sinking lusitaniaUS economic and political ties to Great BritainZimmerman telegram
Unrestricted submarine warfare (in the Atlantic).
Lothar von Arnauld de la Perière (1886-1941) was the most successful U-boat commander of World War I and of any submarine commander in history. Between 1915 and 1918, he made 14 patrols in command of U-35, sinking 189 merchant vessels and two gunboats.
The sinking of the Lusitania was the spark for US entry into WW I.
Unrestricted Submarine Warfare, Sinking of the Lusitiana, the Zimmerman Telegram, and Political ties to Interviews.
Because of enemy "un-restricted" submarine warfare (sinking any ship without allowing innocent personnel a chance to abandon ship).