Answer:
The sinking of the Lusitania, and the Zimmermann note
Step-by-step explanation:
Lusitania was a 32,000-ton ship that was carrying about 173 tons of war munitions for Britain when it was hit by a torpedo sent by Germans on May 7, 1915. This event, which resulted in the death of more than 1,000 people, started to turn American public opinion against Germany and it contributed to the U.S. entry into World War I later on.
The Zimmermann Telegram also drew the U.S. into the war on the side of the allies. This telegram was intercepted and deciphered by British code breakers and later sent to the U.S. in February of 1917. The telegram was a secret message in which the German foreign secretary, Arthur Zimmermann, proposed Mexico an alliance in the case of war between the U.S. and Germany, promising Mexico financial and territorial rewards for its support. Two months later, in April, the U.S. entered the war.