What events changed american public opinion about the war and eventually caused the united states to declare war on germany?

Two major events changed American public opinion about World War I including:

1) Sinking of the Lusitania- This British ship contained over 100 American citizens and was sunk by a German U-Boat. It was reported that this ship did not contain weapons and it was portrayed as a vicious attack by the Germans. Ultimately, over 100 Americans died due to this attack, angering the American public.

2) Zimmerman Telegram- This secret telegram was supposed to be sent directly from the German government to the Mexican government. The Germans wanted to create a secret alliance with Mexico. The Germans wanted Mexico to invade the US in order to prevent them from helping the Allied powers during World War I. The telegram never reached the Mexican government and was intercepted by the Allied powers. After the American public found out about this telegram, they became more supportive of the US joining World War I.

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