The Confederates win the battle of Gettysburg. The British and French agree to support Confederate independence. Seeing the formation of the South as a nation Lincoln agrees to open up negotiations to keep America together.
The terms for the CSA rejoining the USA are the end of slavery with the South being reparated for each one and the loss of each Confederate soldier, Lincoln must step down, no tariffs for or any fees for dealing with foreign countries for the South, and for Britain and France the Monroe Doctrine must be ignored.
In 1864 the president decides to aid France in its ongoing war in Mexico. Secretary Seward deciding that in exchange for America's help the USA should receive Baja. Alaska is not bought from the Russians. Soon after is the British-Spanish war that results in Britain getting Cuba and the Philippines.
The 1890s herald the Great land grab with USA, France and Great Britain trying to seize as much of the Caribbean and Central America as possible. Seeing Britain's and France's growing power and influence in Central and South America the USA slowly begins severing ties with the two countries.
This is my first attempt at an topic on this site. Hopefully I'm not using someone else's ideas. Don't be afraid to tell me what I'm doing or directions I can take this.