08 March 1917,
When a group of Petrograd workers began a general strike, the February Revolution broke out. I. The country was involved in the World War and scarcity was the cause. Bread was their main demand and the rest of the city’s workers quickly came together. The protests were initially attacked by soldiers, who joined the workers within a few days. Within a few days Tsarra had to abdicate. In honor of the women who started the strike, today was declared Working Women's Day in the Soviet Union, now widespread throughout the world.
Source:
Cincia Fencia and Daniel Gaido, Feminism and Movement of Socialist Women in the Russian Revolution.