The BSP was formed in 1911. It was not the only Socialist Party in Britain. There was a great deal of factional struggle between it and the Social Democratic Federation, formed by H.M. Hyndman in 1908. The two organisations maintained an uneasy co-existence until 1916 when the Hyndman faction was defeated and the BSP was left to pursue its anti-war policy unhindered. The SDF under Hyndman’s leadership
advocated a ‘big navy’ policy and in contrast to the BSP who opposed militarism and the First World War from the outset. The defeat of the Hyndman faction effectively meant that the BSP was the only marxist organisation in Britain, and thus it played an important role in the formation of the Communist Party in 1920.