the American revolution caused it to be signed when they won and became free
The French came to join alliances with the colonists.
Also, it was the first war won by the Americans.
It was John Tyler.
Tyler's opponents regularly called him "His Accidency" and addressed correspondences to him as "Vice President" or "Acting President" (letters which he returned unopened).
When his term ended in 1845, he did not seek election.