How did the sinking of the Lusitania and the Zimmerman note both play a role in the us entering WW1?

The American public was already shocked and horrified from the sinking of the Lusitania and the constant attacks on their ships, The Zimmerman note was the last straw since it finally turned the publics opinions from anti-war to pro-war.

i'm free to do it

explanation:

your mothers brothers brother in law would be your father.