The Arvida strike began 24 July 1941, when some 700 workers in the Aluminium Co of Canada (Alcan) in Arvida, Québec, spontaneously walked off the job. The next day the strike spread to 4500 workers, who decided to occupy the plant. Since the industry had been classified as essential to the war effort, the strike was illegal under federal law. A commotion resulted when Minister of Munitions and Supply C.D. Howe told the press that 300 men had seized the factory and enemy sabotage was suspected. Consequently, two companies of soldiers were sent to Arvida to protect the factory.
Work resumed 4 days later and negotiations began, with the union as intermediary, assisted by federal conciliators. A subsequent royal commission rejected the sabotage theory, concluding that the strike had been the result of workers' frustration over their long struggle for better salaries and working conditions. The immediate catalysts to the strike had been deductions from the July 23 pay envelopes and a stifling heat wave. The company made amends several days later by giving a slight increase in salaries and in cost-of-living bonuses.