They won the war and paid Mexico
The Black Death was a huge plague spread by Rats that was very contagious, it devastated Europe and killed many people, once it was done away with new tides turned and new foot holds of power proceeded forward due to knew tech, and different method of thinking.
To give the United States the power of self-government. While it was a power move to make it evident to Britain that they wanted freedom, it was more so based off the fact that they realized they wanted to have their own system instead of working under Britain’s harsh ruling.