Upsets. They happen all the time in sporting competitions of all sorts. Horse racing in particular—with so many factors influencing the outcome of each race—is filled with stories of heavy favorites that were beaten by unexpected longshots.

In 1919, a 2-year-old colt named Man o’ War was beaten in the Sanford Memorial at Saratoga. Such was his budding reputation that the loss was considered - even at the time - to have been a major surprise. However, when one considers that Man o’ War eventually retired as arguably the greatest Thoroughbred in the history of U.S. racing - with a record of 20 wins from 21 starts - his defeat in the Sanford Memorial becomes almost unfathomable. It may have been the biggest upset of any race in the 20^th century.

Heading into the Sanford, Man o’ War was already an experienced colt with five stakes wins under his belt. He started his career on June 6 at Belmont Park, winning a maiden race by six lengths; three days later, he won the Keene Memorial at Belmont with complete ease by three lengths. Twelve days later, it was on to Jamaica Racetrack, where he won the Youthful Stakes by 2 ½ lengths eased up, and two days after that, he cruised to victory in the Hudson Stakes at Aqueduct while carrying 130 pounds.

Nowadays, it’s hard to imagine any horse - let alone a 2-year-old - winning four races in the span of 18 days, but Man o’ War was just getting warmed up. On July 5, he won the Tremont Stakes at Aqueduct, then took a brief rest to gear up for the prestigious Saratoga meet. Then, as now, Saratoga was the track where the best horses gathered to battle for supremacy of major races with several rich stakes races for 2-year-olds on the agenda, it was also the place where juvenile championships could be won.

Man o’ War’s first excursion at Saratoga proved to be very successful. Showing even more speed and brilliance than usual, he was never challenged in the U.S. Hotel Stakes and won eased up by two lengths while carrying 130 pounds. So much the best was Man o’ War that little attention was paid to the runner-up, a colt that would be remembered as much for his eerily apropos name than for his soon-to-be unimaginable accomplishment on the racetrack.

In what might be the most fitting racehorse name of all time, the colt’s name was Upset.

On August 13, 11 days after the U.S. Hotel Stakes, seven Thoroughbreds lined up at Saratoga to contest the Sanford Memorial. Not surprisingly, Man o’ War was favored to win, but Golden Broom – the impressive winner of the Saratoga Special earlier in the meet - was believed to have a chance at beating Man o’ War.

The weather was cloudy and warm as the horses milled around behind the starting barrier. At the time, starting gates were not in use at Saratoga, and horses had to be lined up behind a flexible barrier that would be raised out of the way to mark the start of the race. Trying to line up seven young Thoroughbreds without a starting gate can be a tricky task, and the horses were at the post for four minutes before C. H. Pettingill, who was filling in for Saratoga’s regular starter, sent the field on the way.

There was only one problem: Man o’ War didn’t get off to a good start.

To this day, there remains debate about exactly which direction Man o’ War was facing when the barrier rose and the race began. With no video footage of the race, and no pictures of the start, only eyewitness accounts remain, and while they dispute the exact details - was Man o’ War facing generally forward, somewhat sideways, or even backward at the start? - there is no disagreement that Man o’ War got off to a very poor start and conceded a significant advantage to his rivals.

In a longer race, a poor start might not have been an issue, but in a six furlong sprint like the Sanford, such a beginning would spell disaster for an ordinary horse. But Man o’ War was far from an ordinary horse, and despite getting left behind at the start, Man o’ War surged into contention as the field moved down the backstretch. By the time the field had run a quarter-mile, Man o’ War had rallied to within two lengths of the pace set by Golden Broom and Upset.

But Man o’ War’s troubles wouldn’t end there. His jockey, Johnny Loftus, made the fateful decision to send Man o’ War inside of horses, and the unbeaten colt found himself boxed in along the rail with nowhere to run. Ahead of him, Golden Broom and Upset were still running strongly; to his outside, Donnacona was blocking the way out.

Around the turn and into the homestretch, Man o’ War remained trapped on the inside, and in the final furlong he was still in third place. But suddenly, the box began to dissolve; Donnacona and Golden Broom began to tire, and jockey Bill Knapp urged Upset into the lead. Loftus guided Man o’ War to the outside and the chestnut colt unleashed a burst of speed; with an impressive rally, he closed the gap separating him from Upset.

But it was far from a fair fight. Man o’ War, by virtue of his previous accomplishments, was carrying 130 pounds compared to 115 on Upset. With his lightweight impost, Upset was still running strongly on the lead, and although Man o’ War was charging hard, there wasn’t enough time to overcome the deficit.

As the two colts crossed the finish line, Upset was in front by just over a neck.

In the aftermath of the race, racing experts almost universally acknowledged Man o’ War’s superiority, and the colt’s reputation was enhanced by his courageous performance in defeat. In the August 14, 1919 edition of the Daily Racing Form, writer J. L. Dempsey said “Greater in defeat than he was before, was the general verdict of the great throng that witnessed Man o’ War’s terrific struggle to overcome the many obstacles that beset him in his effort to add the Sanford Memorial to his list of victories … without attempting to detract from the merits of [Upset’s] performance, Man o’ War proved himself in the running unquestionably the best. It was Upset’s advantage at the start, coupled with fifteen pounds weight concession, a perfect ride he received from Knapp and his success in saving ground on the stretch turn that brought his triumph over Man o’ War. Had the race been a sixteenth farther the finish would have been reversed.”

In his very next race Man o’ War turned the tables and beat Upset with ease in the Grand Union Hotel Stakes at Saratoga, then ended the season with wins in the prestigious Hopeful Stakes and Futurity Stakes. The following year, he would win eleven more races while carrying as much as 138 pounds, and the margins of some of his victories - 20 lengths in the Belmont Stakes, 15 lengths in the Jockey Club Gold Cup, and a staggering 100 lengths in the Lawrence Realization - were astonishing. With the benefit of hindsight, it’s almost impossible to believe that Man o’ War ever lost the Sanford Memorial … but as the old saying goes, “that’s why they run the races.”