(A) ** Unrestricted Submarine Warfare
(B) Fourteen Points
(C) Trench Warfare
(D) Total War
EXPLANATIONS BELOW
Concept note-1: -Unrestricted submarine warfare was first introduced in World War I in early 1915, when Germany declared the area around the British Isles a war zone, in which all merchant ships, including those from neutral countries, would be attacked by the German navy.
Concept note-2: -They hoped to break the British stranglehold blockade of crucial German supply ports and knock Britain out of the war within the year. U-boats resumed unrestricted attacks against all ships in the Atlantic, including civilian passenger carriers.
Concept note-3: -First Phases of Submarine Warfare In February 1915, German U-Boats began to attack all merchant vessels in British waters. German U-Boats typically allowed the crews of the ships to disembark before the vessel was sunk, usually by deck gun fire instead of torpedoes, as U-Boats carried a limited number.
Concept note-4: -What was the German policy that called for the sinking of all ships, armed or not, that carried supplies to the Allies? Unrestricted submarine warfare.
Concept note-5: -There have been four major campaigns of unrestricted submarine warfare, one in World War I and three in World War II: The U-boat campaign of World War I, waged intermittently by Germany between 1915 and 1918 against Britain and her allies.