 Complete the following phrase:  In January 1905, the massacre of protesters that came to be known as Bloody Sunday took place in St. Petersburg, sparking the civil unrest known as the Revolution of 1905. In response to these events, Lenin urged Bolsheviks in the Empire to take a greater role in the unrest, encouraging violent insurrection against the Tsarist establishment, including police and the Black Hundreds. He also insisted that the Bolsheviks split completely with the Mensheviks, although many Bolsheviks, among them close colleagues like Gusev and Zemlyachka, disagreed with him. Thus, both groups were invited to the 