While attending Morgan College in 1915, Robert Earl Johnson would stretch his legs by chasing the trolleys that rattled through the streets of West Baltimore. Running as a sport was new to him, but it stirred something in the competitive Johnson. He entered road races and blossomed into a national champion, a two-time Olympian and a dual medalist in the 1924 Summer Games in Paris.

A century ago, on a sweltering July day that turned many of the world’s top distance runners into French toast, Johnson placed third in the grueling 10,000-meter cross country event, capturing the bronze medal for the U.S. (as well as a silver in team cross country) to earn acclaim as the greatest American distance runner of the era.

How demanding was that race? Of the 39 athletes who started, only 15 finished. “Twenty-four fell far back along the route, where many lay as dead men, face down under the blazing sun,” The Philadelphia Inquirer’s Grantland Rice wrote. “The cross-country route looked like the war area, with dead scattered as from machine-gun fire.

There has never been, in the history of track athletics, such terrific strain thrown upon the last limit of human endurance.” One by one, the remaining runners, including Johnson, wobbled toward the finish, the New York Daily News reported: “Exhausted by their efforts, and with their lungs crying for air, the athletes plunged into the immense bake oven within the steaming walls of [the Olympic] stadium, where the air was stifling .