Question

which incident provoked USA to enter into 1 world war

Answer 1

Once Germany had decided onunrestricted submarine warfare in January 1917, and knowing it would beattacking all American ships in the North Atlantic, it tried to line up new allies, especially Mexico. Arthur Zimmermann, the German foreign minister, sent the Zimmermann Telegram to Mexico on January 16, 1917.

Answer 2

In January 1917 Germany decided to resume unrestricted submarine warfare with no warning to passengers or crews. Its goal was to starve Britain into surrender, although it realized that it would almost certainly bring the United States into the war. Germany also made a secret offer to help Mexico regain territories lost in the Mexican–American War in an encoded telegram known as the Zimmermann Telegram, which was intercepted by British intelligence. Publication of that communique outraged Americans just as German U-boats started sinking American merchant ships in the North Atlantic. Wilson then asked Congress for "a war to end all wars" that would "make the world safe for democracy", and Congress voted to declare war on Germany on April 6, 1917.