Germans’ descision the continue the policy of submarine warfare and the “Zimmerman telegram” is the main reasons the United States entered the War of World War One. The submarine warefare was know for the desperate effort to counter Britsh blockade of Germany. The sinking of American ships heading for England was caused by the submarine warfare. The US pressure cause them to abandon it. Woodrow Wilson renounced his position of neutrality because of the resumption that came with it. His war speech to congress demonstrates: “The new policy has swept every restriction aside. Vessels of every kind, whatever their flag, their character, their cargo, their destination, their errand, have been ruthlessly sent to the bottom without warning and without