History.com: The 1936 Strike That Brought America's Most Powerful Automaker to Its Knees

Over 136,000 GM workers participated in a sit-down strike in Flint, Michigan. In Flint, Michigan, the United Auto Workers staged the first successful sit-down, forcing General Motors to come to terms. It was a major victory and the sit-down spread to other areas. Eventually, the strike spread to 17 GM plants over 44 days. GM tried to fight the strike in court, but the strikers ignored an injunction and Murphy refused to enforce it with the National Guard. Then President Franklin Delano Roosevelt urged GM to negotiate. The combination of those pressures got GM to the negotiating table.