On July 1, 1971, members of the International Longshore and Warehouse Union (ILWU) walked out against their employers, represented by the Pacific Maritime Association (PMA).
The union's goal was to secure employment, wages, and benefits in the face of increased mechanization, shrinking workforce, and the slowing economic climate of the early 1970s.
The old 'break bulk' style of loading and unloading, which required a large number of workers, was dangerous, and expensive for employers, and had become obsolete.
The introduction of containerization increased port productivity, and required fewer laborers to load and unload cargo.
When the International Longshoremen's Association (ILA) went on strike for four days, it was decided that Taft-Hartley must be invoked in order to avoid further damage to the economy.
Because of fear that it would extend the strike by giving the longshoremen work, the PMA stopped shipment of military equipment to Vietnam, prompting Congress to pass arbitration legislation on February 7, 1972.