Modern conventions are often derided for stagey predictability. They haven't always been so:
1860 First GOP convention that nominated a winning presidential candidate.
William H. Seward of New York was the Republican front-runner as the convention began in Chicago. Abraham Lincoln had other ideas, but few outside of Illinois gave him a chance. Republicans built a convention center called the Wigwam, which could hold 10,000 people at a time when Chicago had 100,000 residents. There were no primaries, so the convention would pick the candidate. Seward failed to win on the first ballot, and the intrigue began. Lincoln's supporters printed fake tickets and stuffed the Wigwam with their supporters. They also kept Seward's supporters isolated from other delegations. Momentum shifted after the first ballot. On the third ballot, Lincoln won.
1912 First GOP primaries; last party split.
Republicans held their first primaries, but only in 12 of the 48 states. Former President Theodore Roosevelt overwhelmingly won most of them and sought the nomination at the convention in Chicago. His opponent was a man he had once chosen as his successor, President William H. Taft, who had won only the Massachusetts primary. But Taft held sway over the Republican National Committee. And since 36 states did not have primaries, party politics — not voters — controlled those delegations. An infuriated Roosevelt told his supporters to abstain in a raucous convention in which delegates shouted "choo, choo, choo" because they felt they were being railroaded — in the end, they walked out. Taft won the nomination. But Roosevelt left the party and ran as a Progressive, better known as the Bull Moose Party. In the general election, he got more votes than Taft. The split handed the election to Woodrow Wilson.
1976 Last contested GOP convention.
Gerald Ford was never elected president. The top Republican in the House, he became vice president when Spiro Agnew quit, then president when Richard Nixon resigned during the Watergate scandal. Ford had promised not to run for president but changed his mind and faced a challenge on the right from Ronald Reagan.
Though Reagan's campaign started slowly, he gained momentum. And by the time both candidates reached the convention in Kansas City, neither man had enough delegates to win the nomination outright. But through maneuvers and machinations, Ford eked out a first-ballot win. He was helped by a Reagan blunder in which he promised to put a northeastern progressive Republican on his ticket if nominated. That promise backfired, alienating some of Reagan's Southern supporters.