Treaty of Mentor
The Treaty of Mentor was not an actual treaty but it was a unifying moment for the Republican Party after a contested convention in 1880. The nomination of James Garfield after the 36th ballot was unexpected and factions among Republicans who supported other candidates led to an appearance of division in the party.
Former-President Ulysses Grant and other prominent Republicans would meet Garfield at his residence in Mentor, Ohio. The meeting was both a get-to-know moment and a chance to showcase Republicans in solidarity. The press that gathered in Mentor would dub the meeting a treaty. Also significant, it was the beginning of the first ever 'Front Porch Campaign' for president.
James Garfield would be elected President and assassinated all within one year.