The Russian Revolution of 1905, also known as the First Russian Revolution, was a revolution in the Russian Empire which began on 22 January 1905 and led to the establishment of a constitutional monarchy under the Russian Constitution of 1906, the country's first formal constitution. The revolution was characterized by mass political and social unrest including worker strikes, peasant revolts, and military mutinies directed against Tsar Nicholas II and the autocracy, who were forced to establish the State Duma legislative assembly and grant certain rights, though both were later undermined.