The Industrial Workers of the World had attempted to organize longshoremen, sailors and fishermen in the 1920s through their Maritime Workers Union. Their largest strike, in San Pedro, California in 1923, bottled up shipping in that harbor, but was crushed by a combination of injunctions, mass arrests and vigilantism by the American Legion. While the IWW was a spent force after that strike, syndicalist thinking remained popular on the docks. Longshoremen and sailors on the West Coast also had contacts with an Australian syndicalist movement that called itself the "One Big Union" formed after the defeat of a general strike there in 1917.
The Communist Party had also been active in the area in the late 1920s, seeking to organize all categories of maritime workers into a single union, the Maritime Workers Industrial Union (MWIU), as part of the drive during the Third Period to create revolutionary unions. The MWIU never made much headway on the West Coast, but it did attract a number of former IWW members and foreign-born militants, such as Harry Bridges, an Australian-born sailor who became a longshoreman after coming to the United States.
Those militants published a newspaper, "The Waterfront Worker", that focused on longshoremen's most pressing demands: more men on each gang, lighter loads and an independent union. While a number of the individuals in this group were Communist Party members, the group as a whole was independent of the party: although it criticized the International Seamen’s Union (ISU) as weak and the International Longshoremen's Association (ILA), which had its base on the East Coast, as corrupt, it did not embrace the MWIU, but called instead for creation of small knots of activists at each port to serve as the first step in a slow, careful movement to unionize the industry.
Events soon made the MWIU wholly irrelevant. Just as the passage of the National Industrial Recovery Act had led to a spontaneous explosion in union membership among coal miners in 1933, thousands of longshoremen now joined the fledgling ILA locals that reappeared on the West Coast. The MWIU faded away as party activists followed the mass of West Coast longshoremen into the ILA.
These newly emboldened workers first went after the "blue book" union, refusing to pay dues to it and tearing up their membership books. The militants who had published "The Waterfront Worker", now known as the "Albion Hall group" after their usual meeting place, continued organizing dock committees that soon began launching slowdowns and other types of job actions in order to win better working conditions. While the official leadership of the ILA remained in the hands of conservatives sent to the West Coast by President Joseph Ryan of the ILA, the Albion Hall group started in March, 1934 to press demands for a coastwide contract, a union-run hiring hall and an industrywide waterfront federation. When the conservative ILA leadership negotiated a weak "gentlemen's agreement" with the employers that had been brokered by the mediation board created by the Roosevelt Administration, Bridges led the membership in rejecting it.
The sticking point in the strike was recognition: the union demanded a closed shop, a coastwide contract and a union hiring hall. The employers offered to arbitrate the dispute, but insisted that the union agree to an open shop as a condition of any agreement to arbitrate. The longshoremen rejected the proposal to arbitrate.
The Roosevelt Administration tried again to broker a deal to end the strike, but the membership twice rejected the agreements their leadership brought to them. The employers then decided to make a show of force to reopen the port in San Francisco. On Tuesday, July 3, fights broke out along the Embarcadero in San Francisco between police and strikers while a handful of trucks driven by young businessmen made it through the line.
Some Teamsters supported the strikers by refusing to handle "hot cargo" - goods which had been unloaded by strikebreakers though the Teamsters leadership was not as supportive. By the end of May Dave Beck, president of the Seattle Teamsters, and Mike Casey, president of those in San Francisco, thought the maritime strike had lasted too long. They encouraged the strikers to take what they could get from the employers and threatened to use Teamsters as strikebreakers if the ILA didn't return to work.
Hostilities picked up again that afternoon, when a group of strikers surrounded a police car and attempted to tip it over. The police fired shotguns in the air, then fired their revolvers at the crowd. One of the policemen fired a shotgun into the crowd, killing a striking seaman and a strike sympathizer, Nicholas Bordois and Howard Sperry.
Strikers immediately cordoned off the area where two picketers had been shot, laying flowers and wreaths around it. Police arrived to remove the flowers and drive off the picketers minutes later. Once the police left, the strikers returned, replaced the flowers and stood guard over the spot.
As strikers carried wounded picketers into the ILA union hall police fired on the hall and lobbed tear gas canisters at nearby hotels. At this point someone reportedly called the union hall to ask "Are you willing to arbitrate now?"
Under orders from California Governor Frank Merriam, the California National Guard moved in that evening to patrol the waterfront. Similarly, federal soldiers of the United States Army stationed at the Presidio were placed on alert. The picketers pulled back, unwilling to take on armed soldiers in an uneven fight, and trucks and trains began moving without interference. Bridges asked the San Francisco Labor Council to meet that Saturday, July 7, to authorize a general strike. The Alameda County Central Labor Council in Oakland considered the same action. Teamsters in both San Francisco and Oakland voted to strike, over the objections of their leaders, on Sunday, July 8.
San Francisco Mayor Angelo Rossi declared a state of emergency. Some federal officials, particularly Secretary of Labor Frances Perkins, were more skeptical. Roosevelt later recalled that some persons were urging him to steer the USS Houston, which was carrying him to Hawai'i, "into San Francisco Bay, all flags flying and guns double-shotted, and end the strike." Roosevelt rejected the suggestion.
The strike lasted four days. Non-union truck drivers joined the first day; the movie theaters and night clubs closed down. While food deliveries continued with the permission of the strike committee, many small businesses closed, posting signs in support of the strikers. Reports that unions in Portland and Seattle would also begin general strikes picked up currency.
That, however, left the striking seamen in the lurch: the employers had refused to arbitrate with the ISU unless it first won elections on the fleets on strike. While Bridges, who had preached solidarity among all maritime workers and scorned arbitration, apologized to the seamen for the longshoremen's vote, the President of the ISU urged them to hold out and to burn their "fink books", the membership records of the company union to which they had been forced to pay dues.
On July 17, 1934, the California National Guard blocked both ends of Jackson Street from Drumm to Front with machine gun mounted trucks to assist vigilante raids, protected by SFPD, on the headquarters of the Marine Workers' Industrial Union and the ILA soup kitchen at 84 Embarcadero. Moving on, the Workers' Ex-Servicemen's League's headquarters on Howard between Third and Fourth was raided, leading to 150 arrests and the complete destruction of the facilities. The employer's group, the Industrial Association, had agents riding with the police. Further raids were carried out at the Workers' Open Forum at 1223 Fillmore street and the Western Worker building opposite City Hall that contained a bookstore and the main offices of the Communist Party, which was thoroughly destroyed. Attacks were also perpetrated on the 121 Haight Street Workers' School and the Mission Workers' Neighborhood House at 741 Valencia Street. A police spokesperson suggested that "maybe the Communists staged the raids themselves for publicity".
General Hugh Johnson, then head of the National Recovery Administration, gave a speech urging responsible labor leaders to "run these subversive influences out from its ranks like rats". A lawyer for the American Civil Liberties Union was kidnapped and beaten, while vigilantes seized thirteen radicals in San Jose and turned them over to the sheriff of an adjoining county, who transported them to another county. In Hayward in Alameda County someone erected a scaffold in front of the city hall with a noose and a sign stating "Reds beware". In Piedmont, an upscale community bordering both Oakland and Berkeley, the chief of police prepared for a reported attack by strikers on the homes of wealthy ship-owners.
The arbitration award issued on October 12, 1934 allowed the ILA to cement that power. While the award put the operation of the hall in the hands of a committee of both union and employer representatives, the union was given the power to select the dispatcher. Since longshoremen were prepared to walk out if an employer refused to accept a worker dispatched from the hall, the ILA soon controlled hiring on the docks, causing the employers to complain that the union wanted to "sovietize" the waterfront. Discharge itself was a mild penalty, since the worker could obtain other employment through the hiring hall.
The union soon exploited the "quickie strike" to extract many concessions from employers. Similarly, even though an arbitrator held that the 1935 Agreement prohibited sympathy strikes, the union's members nonetheless refused to cross other union's picket lines. Longshoremen also refused to handle hot cargo intended for non-union warehouses that the union was attempting to organize.
The ISU acquired similar authority over hiring, despite the philosophical objection of the union's own officers to hiring halls and a far less generous arbitration award, by the same means. The ISU used this power to drive strikebreakers out of the industry.
The rift between the seamen's and longshoremen's unions only deepened and became more complex in the years to come as Bridges fought with the Sailors Union of the Pacific over labor and political issues. The West Coast district of the ILA broke off from the International in 1937 to form the International Longshoremen's Union, later renamed the International Longshoremen's and Warehousemen's Union after the union's "march inland" to organize warehouse workers, then renamed the International Longshore and Warehouse Union in recognition of the number of women members.
The arbitration award also gave longshoremen a raise to ninety-five cents an hour for straight time work, just shy of the dollar an hour it demanded during the strike, and a contract that applied up and down the coast.
The ILWU recognizes "Bloody Thursday" by shutting down all West Coast ports every July 5. The ILWU has frequently stopped work for political protests of, among other things, Italy's invasion of Ethiopia, fascist intervention in Spain's civil war, South Africa's system of apartheid and the Iraq War.