How Germany Delayed US Entry into WWI

Germany's actions that postponed American intervention until April 1917:

1. Unrestricted Submarine Warfare (Feb 1917) – Sinking neutral ships without warning; killed Americans, outraged public.
2. Lusitania Sinking (May 1915) – U-boat torpedoed British liner; 128 Americans died. Turned US opinion sharply anti-German.
3. Zimmermann Telegram (Jan 1917) – Secret German proposal to Mexico: ally with Germany, attack US, regain TX/NM/AZ. Intercepted by British, published in US press, inflaming sentiment.

These combined to overcome isolationism; US declared war 6 April 1917.