The main reason why the US joined the war was because multiple attack on passenger and merchant ships with submarine attacks .The final straw was when the RMS Lusitania by a German u-boat going to Liverpool England .
The Stamp Act of 1765 was levied mainly at the American Colonists in order for the British to make money off of them. The colonists did not want the stamp act, and stated that it was unconstitutionanal, and became extremely violent. Parliament repealed the Stamp Act in 1766, but passed another one in a different name that includes what the Stamp Act had in it.
hope this helps
The colonists became extremely violent* is key
A person or group besides the two primarily involved in a situation, especially a dispute.
