On Tuesday, November 1, 1938, two horses stepped onto Baltimore’s Pimlico Race Course for a long-awaited match race. The overwhelming favorite was the exquisite, near-black War Admiral, who had won the Triple Crown the previous year. His opponent was a plain brown wrapper of a horse, a five-year-old ex-claimer named Seabiscuit. Forty thousand tans had ditched work to cram into the track, and even President Roosevelt halted a cabinet meeting to hear the race call.

In the days leading up to the race, Seabiscuit was the underdog–and for good reason. Match races favor the horse who seizes the early lead, and “the Biscuit” was a so-so starter who liked to stalk his rivals before mowing them down. War Admiral, by contrast, was an explosive starter. He was also so averse to starting gates that his owner insisted on an old-fashioned “walk-up” start, with a flag and bell to begin the race. For an old dog like Seabiscuit, walk-up starting would be a formidable new trick. Worse still, War Admiral had drawn the favorable inside post position.

But Seabiscuit’s trainer, Tom Smith, had one clear advantage: His horse was a willing and remarkably fast learner. Smith had already used the training technique known as classical conditioning to control Seabiscuit’s overeating. Now the trainer devised a new conditioning plan. Smith began by fashioning a homemade starter’s gong. Then he fitted Seabiscuit’s jockey, George Woolf, with spurs, and led horse and rider to the training track. Woolf walked the horse to the starting line, and Smith struck the gong. Breaking into frantic urging, the jockey squeezed Seabiscuit with his spurs, sending the horse bounding forward. After less than a furlong, Woolf pulled up, returned to the starting line and repeated the drill. In just four starts, Seabiscuit formed such a powerful association between the gong and the spurring that he lunged forward involuntarily the instant the gong was struck.

Smith’s next step was to discard the spurs and line Seabiscuit up against several lightning-fast sprinters. He repeatedly drilled the horses in gong-started walk-ups, ordering Woolf to drive Seabiscuit off the line as hard as he could. Overnight, Seabiscuit became a veritable catapult, hardwired to blast off the line at the sound of Smith’s gong.

Race day dawned with the momentous discovery that Pimlico had no portable starting bell. Smith cheerfully offered his homemade gong to starter George Cassidy. The horses walked to the line, and Cassidy raised his arm to strike the gong. After two false starts, the rivals’ noses passed over the line together, and the gong sounded.

To everyone’s astonishment, Seabiscuit shot to the lead. Before the first turn, with his horse two lengths in front, Woolf steered Seabiscuit to the rail and then reeled him in to conserve his strength. War Admiral’s jockey, Charley Kurtsinger, swung his horse to the outside and drew even down the backstretch. For nearly half a mile, the two ran head to head.

Midway around the far turn, with the crowd roaring, War Admiral pushed his nose in front. But one glance at the other horse convinced Woolf that the rally had taken its toll. “War Admiral’s eye was rolling wildly in its socket, as though the horse was in agony,” he said later. “I knew we had him right then.” Woolf gave Seabiscuit a shout, and the little brown horse delivered a final burst of speed, galloping to a four-length victory in a track-record 1:56.6.

Seabiscuit would go on to win his greatest race, the Santa Anita Handicap, in 1940 and then retire to stud. But his match race with War Admiral stands out as a high point of the trainer’s art. Thanks to Tom Smith’s keen understanding of the conditioning process, one of the greatest showdowns in sporting history was over at the start.