When world war i first started in europe, the united states stayed neutral. what caused the united states to change its position and join the war on the side of the allies?
The sinking of The Lusitania by a German U-boat and the Zimmerman Telegram in which it was rumored that Germany offered Mexico (a neutral country) to help win its territory back from the U.S. if they joined the war on the side of the Triple Alliance.
