On May 15, 1919 the Winnipeg Trades and Labour Council called a General Strike after negotiation in the metalworking and building trades broke down. Although only 12,000 workers in Winnipeg were unionized, 30,000 joined the strike within hours of the start. A wave of strikes occured accross Canada in support but died out quickly. Although the strike organizers maintained essential services a large commitee was formed to quash the strike; to discredit the leaders of the strke the opponents claimed that the strike was communist based. When it became apparent that the city police supported the strike the mayor replaced them and called in the support of the RNWMP from the federal government. When the RNWMP tried to break up a demonstration on June 21, 1919, by war veterans they were resisted and fired a volley into the crowd; two men were killed and many others were injured. The police then made mass arrests of anyone remotely connected to the strike including two aldermen and an MLA. On June 26, 1919 the strike leaders who had not been arrested, ended the strike.