B. the constant German sinking of trading vessels resulting in the loss of lives. Germany Decides that it will sink all ships nearing Britain. Germany revokes the Sussex Pledge (1916) Because if the allies are weakening Germany thinks that it can really quickly win before the U.S. can come in an save the day because it takes a lot of time to train people for war. Wilson breaks of diplomatic relations with Germany U.S. doubles the size of army and builds new warships, it becomes clear that the U.S will join the allies the question is when will they join the allies.