MCI didn't seem like a giant killer at first. It was a startup that sold long-distance services via microwave towers to truck drivers. But chairman William McGowan, a hard-living son of a railroad engineer, led his company to do just that. Rather than duck Ma Bell's assaults (predatory pricing), MCI took her head on, filing a case that would lead to the monopoly's breakup -- and an antitrust playbook that others would use against Microsoft decades later. In 1980 a jury awarded MCI $1.8 billion. Two years later the government ruled Ma Bell a monopoly no more. David had slain Goliath.
Seven tales of competition that changed business forever. Available free to subscribers on Fortune's tablet apps.