After the dissolution of the Revolutionary Communist Party, Ted Grant and his supporters were expelled from the RCP's successor The Club in 1950 and formed the International Socialist Group.
They went on to fuse with supporters of the International Secretariat of the Fourth International in Britain as the Revolutionary Socialist League in 1956 and were recognised as the official British section at its fifth world congress in 1957.
[2] It was an entryist group within the Labour Party that published Socialist Fight.
However, the League registered substantial political differences at the 1965 World Congress, and failed to integrate other supporters of the International in Britain.
In 1964, the RSL founded the newspaper Militant and the group itself soon became known by this name, although the official name was still used internally.