1. Shift in U.S. Neutrality the other key reasons

2. War at Sea Both sides attempt blockade of enemies ports Stop the transportation of war supplies Affect ability to fight U-boat—early submarines

3. Great Britain vs. Germany Great Britain Britain—mined the North Sea, cut off Germany navy Seized U.S. ships going to neutral nations Blacklisted U.S. companies that supplied Germany Censored mail from Europe going to the U.S. Germany (U-boats) Created war zone around Great Britain, sink any ship in this area Attack any ship that might carry war supplies to Great Britain

5. The Sinking of the Lusitania 1915 U-boat sank Lusitanian, 197 Americans on board Was carrying ammunition to Britain

6. Results of Blockade U.S. stopped trade with Germany--why German struggle with starvation Americans upset neutral citizens killed (against international law of warring) Germany had posted warnings in NY papers To keep US out of war, Germany promised to stop attacking supply ships of neutral nations

7. Unrestricted Submarine Warfare March 1917, Germany ground war failing, become desperate Start unrestricted submarine warfare again, including U.S. ships Result: Germany perceived as breaking their promise, rule breaker

8. Zimmerman Note British intelligence intercepted message from German foreign minister Arthur Zimmermann to the German ambassador in Mexico Importance Germany breaking international law Trying to sneak up on America

9. U.S. enters WWI April 2 nd 1917 Moral outrage, economic loss (unrestricted U-boat warfare) Germany’s actions appears unlawful— therefore must be punished