In the spring of 1957, a strike wave of monumental proportions rolled across the city of Shanghai. The strikes in Shanghai represented the climax of a national outpouring of labour protest that had been gaining momentum for more than a year. The magnitude of the 1957 strike wave is especially impressive when placed in historical perspective. Major labour disturbances (naoshi) erupted at 587 Shanghai enterprises in the spring of 1957, involving nearly 30,000 workers. More than 200 of these incidents included factory walkouts, while another 100 or so involved organized slowdowns of production. Additionally, more than 700 enterprises experienced less serious forms of labour unrest (maoyari). These figures are extraordinary even by comparison with Republican-period Shanghai when the May Fourth Movement of 1919, the May Thirtieth Movement of 1925, the Shanghai Workers' Three Armed Uprisings of 1926–27 and the protests of the Civil War years gave rise to one of the most aggressive labour movements in world history. In 1919, Shanghai experienced only 56 strikes, 33 of which were connected with May Fourth. In 1925, it saw 175, of which 100 were in conjunction with May Thirtieth. The year of greatest strike activity in Republican-period Shanghai, 1946, saw a total of 280.