What two german actions caused the united states to enter ww1?

The Zimmerman Telegram, which was a telegram that the German Empire had sent to Mexico for them to invade the U.S. and keep them busy from sending troops to Europe. And they had been sinking U.S. civilian ships, that they claimed had weapons on board.

Explanation:

monarchy doesn’t have to have the hereditary element. there have been elective monarchies in the past where you choose your king-for-life and when he dies elect someone else for the job.