It’s a short drive from South Prairie Avenue to another important site. On the evening of September 25, 1925, Spike O’Donnell, the leader of a South Side gang, was walking in front of a drugstore on the northwest corner of Sixty-third Street and Western Avenue. From a car a voice greeted him: “Hello, Spike.” O’Donnell, who’d been left out of one of the early territorial partitions, had always bridled under the ascendancy of Torrio and Capone. “I can whip this bird Capone with my bare fists,” he bragged. He also risked incursions into territory controlled by the rival gang leader Frank McErlane.

The Illinois Association for Criminal Justice labeled McErlane “the most brutal gunman who ever pulled a trigger in Chicago.” The previous year, drinking in an Indiana saloon, Frank’s pals were chiding him about his marksmanship. McErlane drew his pistol, picked out a stranger at the end of the bar, and dropped him with a bullet through the temple.

It was McErlane who hailed Spike O’Donnell that night. Spike responded prudently by diving to the sidewalk. The evening exploded into gunfire. When the fusillade ended and the car sped away, O’Donnell brushed himself off, entered the drugstore, and asked for a drink of water.

Police and reporters were mystified by the volume of fire and by the orderly rows of pockmarks on the building. Today LeVell points out the distinctive gouges around the doorway at 2408 West Sixty-third (the drugstore is now a currency exchange). And today we know the source of the gunfire. McErlane that evening introduced the Thompson submachine gun into the beer wars and into the world’s imagination.

William J. Helmer, in his treatise on the tommy gun, labels it “the Gun that Made the Twenties Roar.” A magazine writer of the time described it as a “diabolical engine of death.” The gun, which weighed twelve pounds, fired .45-caliber pistol ammunition at a rate of more than ten rounds a second. Because its bullets could penetrate a quarter-inch steel plate and stop a moving car, the gun was rejected for police work as a menace to bystanders. Fired on full automatic, it was inaccurate, as McErlane found out. But the volume of fire that it put into one man’s hands generally made marksmanship irrelevant. Gun laws of time covered only “concealable” weapons, so the Thompson, for most of the 1920s, was perfectly legal. Gangs adopted it enthusiastically.