The MNLA was a guerrilla force created by the Malayan Communist Party (MCP). Many MNLA fighters were previously members of the Malayan People's Anti-Japanese Army (MPAJA), another guerrilla force which the British had secretly trained and armed during World War II to fight against the Japanese occupiers. The Communist Party, which had been banned in the pre-war years, was thereafter granted legal recognition by the British after the war as a reward for its wartime effort but had secretly kept some of the MPAJA's weapons for future use. The MCP used violence to support its union organisation, and the British used restrictions, including banishing key communist leaders not born locally, in an attempt to restrict trade union activity. This mutual antagonism climaxed with an armed revolt in 1948, which resulted in the declaration of a state of emergency in June 1948.