Why did the US into World War 1?

Answer 1

The tensions were heightened when in 1915, the British passenger liner the Lusitania was sunk by a German submarine, killing 128 Americans. Then came the German sabotage with the Black Tom explosion of ammunitions, and the Kingsland Explosion, a shell manufacturer. The Germans thought this would hamper the U.S. in joining the war effort. All this time, Wilson was trying to use diplomacy, but that had failed miserably. Wilson's isolationist tendencies finally came to an end and the U.S. entered the war after Germany resumed unrestricted submarine warfare in 1917. This is the very, very short version.