The British Fourteenth Army was a multi-national force comprising units from Commonwealth countries during the Second World War. As well as British Army units, many of its units were from the Indian Army and there were also significant contributions from the British Army's West and East African divisions. It was often referred to as the "Forgotten Army" because its operations in the Burma campaign were overlooked by the contemporary press, and remained more obscure than those of the corresponding formations in Europe for long after the war. For most of the Army's existence, it was commanded by Lieutenant-General William Slim.

The Burma campaign was a series of battles fought in the British colony of Burma. It was part of the South-East Asian theatre of World War II and primarily involved forces of the Allies against the invading forces of the Empire of Japan. Imperial Japan was supported by the Thai Phayap Army, as well as two collaborationist independence movements and armies. Nominally independent puppet states were established in the conquered areas and some territories were annexed by Thailand. In 1942 and 1943, the international Allied force in British India launched several failed offensives to retake lost territories. Fighting intensified in 1944, and British Empire forces peaked at around 1 million land and air forces. These forces were drawn primarily from British India, with British Army forces, 100,000 East and West African colonial troops, and smaller numbers of land and air forces from several other Dominions and Colonies. These additional forces allowed the Allied recapture of Burma in 1945.