At the start of the Great War, the United States and President Woodrow Wilson was adamant about remaining a neutral party to protect its diplomatic relations with both sides, but after several German U-Boat attacks on American merchant and passenger ships, especially the devastating attack on the Lusitania which killed over a thousand US citizens, Wilson felt the pressure from war hawks, including former President Teddy Roosevelt, to enter the war. Wilson aimed to remain neutral and threated US military action if the attacks did not cease, and the Germans agreed, until January 1917, when the attacks resumed. With the continued attacks on merchant vessels and German Foreign Minister Arthur Zimmerman’s attempt to sway Japan and Mexico against the United States, Wilson had no choice but to enter the war. The tides had changed.