made up of Karens, Kachins and Chins. During the war, the British needed manpower, and relaxed the recruitment restrictions, raising a Burman battalion in the 70th Burma Rifles, a Burman company in the 85th Burma Rifles, and seven Burman Mechanical Transport companies. In addition, three companies of Burma Sappers and Miners, made up of mostly Burmans, and a company of Labour Corps, made up of Chins and Burmans, were also raised. All these units began their overseas assignment in 1917. The 70th Burma Rifles served in Egypt for garrison duties while the Burmese Labour Corps served in France. One company of Burma Sappers and Miners distinguished themselves in Mesopotamia at the crossing the Tigris. After the war, the 70th Burma Rifles was reorganised as the 20th Burma Rifles, and the number of companies of Burma Sappers and Miners was reduced from three to one. The British stopped recruiting Burmans, and gradually discharged most of their Burman troops between 1923 and 1925. In 1929, the last Burman company of Burma Sappers and Miners too was disbanded. On 1 April 1937, when Burma was made a separate colony, the ethnic makeup of the 20th Burma Rifles, now the British Burma Army, was approximately 50% Karen, 25% Kachin and 25% Chin. A fourth battalion was added for Burmans but few Burmans bothered to join at any rate. Before World War II began, the British Burma Army consisted of Karen (27.8%), Chin (22.6%), Kachin (22.9%), and Burman 12.3%, without counting their British officer corps. World War II On 28 December 1942, a group of young Burmese independence activists, called the Thirty Comrades, who had received military training by the Japanese, founded the Burma Independence Army (BIA) in Bangkok. The army led by Aung San fought in the Burma Campaign on the side of the Imperial Japanese Army. It saw a significant engagement at Shwedaung near Prome against the British in March 1942. Thousands of young men joined its ranks—reliable estimates range from 15,000 to 23,000. The great majority of the recruits were Burman, with little ethnic minority representation. Many of the fresh recruits lacked discipline. At Myaungmya in the Irrawaddy delta, an ethnic war broke out between Burman BIA men and Karens, with both sides responsible for massacres. The BIA was soon replaced with the Burma Defense Army, founded on 26 August 1942 with three thousand BIA veterans. The army became Burma National Army