13 July 1917: São Paulo general strike

On this day, 13 July 1917, thousands of workers joined a spontaneous strike in São Paulo following the police killing of a 21-year-old shoemaker, José (or Antonio) Martínez, at a demonstration against the high cost of living two days previously. The stoppage soon became a general strike, and workers could only be persuaded to return to work three days later after being given a 10% pay increase. 
More information and sources: https://stories.workingclasshistory.com/article/8481/s%C3%A3o-paulo-general-strike
The strike wave at this time is commemorated by this T-shirt of the Month, made by a workers' co-operative and...