During the First World War members of the British West Indies Regiment experienced racial discrimination, which produced a mutiny in 1918 at Taranto, Italy. In the West Indies themselves, worsening economic conditions led to widespread strikes in 1917 and 1918. The bad experiences of demobilised soldiers led to the trade union movement, producing further strikes in 1919.
The strikes were accompanied by the rise of black consciousness (associated with the leadership of Marcus Garvey) and middle-class demands for increased representation in government. Britain responded to these pressures by considering the improvement of conditions in the sugar industry and the possible federation of certain colonies.
The colonies had distinct constitutional forms - Jamaica and Barbados had constitutional structures that dated back to the 17th century, including bi-cameral assemblies; by contrast, Trinidad and Tobago had the 19th century Crown Colony model of a single-chamber assembly.
Hardship experienced during the depression of the late 1920s accelerated trade union activism and widespread disturbances took place in 1937 and 1938. Following the declaration of Martial Law, Commissions of Enquiry in Trinidad and Tobago and Barbados resulted in a further Royal Commission under Lord Moyne which reported in 1940. Although the commission's broader findings were made public, the abysmal conditions it described were thought likely to undermine morale, and the full report was not published until the end of the war in 1945.
Given the assumption that the West Indian colonies would stay within the Commonwealth, progress towards responsible government was slow. A new constitution that included the right to vote was established in Jamaica in 1944 and reforms were extended to other colonies during the 1950s. Barbados and Jamaica achieved full self-government in 1958 and 1959. The exception was British Guiana, where the British overthrew the elected government under Sir Chedda Jagan in 1953, claiming it had become a communist state.
The British supported a federation, believing that the individual colonies were too small to be viable states. Norman Manley, the Jamaican Prime Minister, supported the idea. Further conferences were held in London in 1953 and 1955, and the British West Indian Federation was instituted in 1958, with only British Guiana refusing to join. The federation capital was Port-of-Spain, Trinidad, and the Prime Minister was Sir Grantley Adams of the Barbados Labour Party.
In the two biggest colonies, Jamaica and Trinidad and Tobago, there was opposition to federation because they would be expected to subsidise the others. Consequently, the federation broke up in May 1962, with Jamaica and Trinidad and Tobago becoming fully independent. In 1968, the Caribbean Commonwealth countries formed a free trade area, CARIFTA, which became the Caribbean Community (CARICOM) in 1973.