MacDonald was the first Labour Party prime minister of Britain, serving in 1924, from 1929 to 1931, and again as part of a coalition government from 1931 to 1935. He joined the precursor of the Labour Party in 1894 and served as its first secretary. MacDonald was elected to Parliament in 1906 and was leader of the Labour party there from 1911 to 1914, until he was forced to resign for opposing participation in WWI. From what other organization was MacDonald expelled for his pacifist stance? Discuss
Source: The Free Dictionary