Before their strike in 1934, dockhands on the West Coast were paid a pittance in exchange for performing bone-crushing physical labor. No matter how heavy or dangerous the cargo, it fell upon the longshoreman to haul it almost entirely by hand: Workers pulled and shoved massive shipments while harbor employers stood on high, dictating their work pace at breakneck speeds.

Despite poor working conditions, thousands of laborers would line the docks each morning in hopes of being one of the lucky “wharf rats” chosen by hiring bosses to work for the day. This system of casual employment—known as the “shape up”—was loathed by the longshoremen, whose livelihoods essentially depended on the daily whims of shipping bosses.

The West Coast Longshoremen’s Strike of 1934 was the culmination of decades of impromptu “wildcat” strikes, none of which yielded any beneficial outcome for longshore workers. But such poor fortunes would reverse following the passage of the National Industry Recovery Act, which granted federal protections to union members. Their rights now guaranteed, dockhands were free to channel their frustrations under one banner, and in the spring of 1934, thousands of them flooded the ranks of the International Longshoremen’s Association (ILA).

The ILA’s West Coast leaders advocated for an end to unfair labor practices. They wanted dock workers granted a one-dollar wage and a six-hour day. Above all, the ILA demanded replacing the daily shape up with guaranteed work through union-run hiring halls. When their requests were rejected, the longshoremen struck. On May 9, 1934, laborers across the coast abandoned their stations; they were soon joined by sailors, engineers, and other maritime workers.

Over the next 83 days, a total of 130,000 workers left their jobs to join in the uprising. The strikers organized a campaign of disruption, picketing en masse and blocking shipments to and from coastal cities. Many rank-and-file members of the Teamsters Union also pledged to reject dock employers’ cargo that had been handled by strikebreakers, further dismantling industry efforts to wrestle revenue from the chaos.

Violence erupted when dock bosses ordered police and strikebreakers to reopen the ports. Full-scale battles raged across the coastline, leaving hundreds injured. The worst onslaught took place on “Bloody Thursday” on July 5: Police moved to clear San Francisco’s eastern port, firing tear gas and live shotgun rounds into crowds of rioting workers. Dozens were hurt and two were killed. Once the bloodshed abated, thousands of longshoremen gathered to march in a show of solidarity for the dead.

The workers’ unity in wake of Bloody Thursday left an impression on the public; so moved were the masses that popular sentiment began shifting to the side of the longshoremen. Dozens of Bay Area labor unions began to call for strikes. On July 14th, a general strike was agreed upon by the San Francisco Labor Council. In response to the departure of over 150,000 workers, San Francisco Mayor Angelo Rossi declared a state of emergency. After four days—and several hundred arrests—the general strike ended when both the ILA and dock employers agreed to arbitration under a special panel convened by President Franklin D. Roosevelt.

With negotiations underway, most dockhands returned to work on July 31. The panel’s final ruling came in October, and awarded the ILA nearly all of its requests. It was decreed that longshoremen would work a six hour day and a thirty hour week and that wages would increase to $0.95 cents for straight time and $1.50 for overtime. Another major victory was the stipulation that longshore workers would be employed through hiring halls whose dispatchers were selected by the ILA. Longshoremen across the coast were now recognized as members of a unifying organization, to be dispatched on jobs “without favoritism or discrimination” due to “union or non-union membership.”

The conclusion of one of America’s longest, dirtiest, and most important labor strikes was a definitive victory for workers. Its outcome only cemented the ILA’s clout among longshoremen; their West Coast membership increased from 1,300 in 1926 to around 12,000 by 1935.