One hundred years ago, between July 16-20 [3-7 in New Style] 1917, a protest movement of workers and soldiers in Petrograd was repelled by military and police attacks, with hundreds of casualties.
It was a key phase in the storm that swept Russia during 1917. It culminated in the October Revolution when, led by the Bolsheviks, the soviets (councils) of workers, soldiers and peasants took power, overthrowing the capitalist Provisional Government that was formed after the February Revolution deposed the Tsar.
