Bloody Sunday was an event which sparked the Revolution of 1905 in Russia. Father Gapon and 200,000 workers were taking a petition to ask the Tsar to improve their wages and working conditions. It was a peaceful event, but upon arriving at the Winter Palace, imperial guards and Cossacks attacked them killing 200, and injuring 800.
Bloody Sunday sparked outrage, and by February the workers began to strike (for better wages and better working conditions. During this time the Tsar's uncle was assassinated as well.
In March and May, the Russian Army and Navy were shamefully defeated by Japan which was a significantly small country in comparison. Furthermore, the sailors on the battleship Potemkin mutinied. This led to people demanding a change in government.
Peasants started to kill landowners and burn and loot their houses in June and July.
In September, a peace treaty was signed between Russia and Japan, which allowed troops to return and put down the rebellions/revolution in European Russia. To keep the Military loyal to the Tsar the government payed them and offered better working conditions.
Although the Tsar had agreed to give the public some of what they wanted, (Duma, Civil Rights, and Uncensored Newspapers) in the October Manifesto, in December when all the troops had returned to Russia, the Tsar took back control using force, as well as sent out troops to take revenge on workers and peasants who had rioted.