French assistance was crucial in securing the British surrender at Yorktown in 1781. The preliminary agreement was in 1782.
Slaves in the Americans during colonial times were treated incredibly poorly. They obvious were not paid for their labor, and were oftentimes beaten to the point of death for no reason.
They were mostly Republican foes of President Wilson, who believed that the League of Nations was just a British fabrication to protect its empire. Because of the opposing factions in the Senate, they could not come to an agreement, and because they could not come to an agreement the United States did not sign the Treaty of Versailles or join the League of Nations.
Hope I helped!
