The British Socialist Party (BSP) was a Marxist political organisation established in Great Britain in 1911. Following a protracted period of factional struggle, in 1916 the party's anti-war forces gained decisive control of the party and saw the defection of its pro-war Right Wing. After the victory of the Bolshevik Revolution in Russia at the end of 1917 and the termination of World War I the following year, the BSP emerged as an explicitly revolutionary socialist organisation. It negotiated with other radical groups in an effort to establish a unified communist organisation, an effort which culminated in August 1920 with the establishment of the Communist Party of Great Britain. The youth organisation the Young Socialist League was affiliated with the party.