The Royal Thai Air Force or RTAF (; ) is the air force of the Kingdom of Thailand. Since its establishment in 1913 as one of the earliest air forces of Asia, the Royal Thai Air Force has engaged in numerous major and minor conflicts. During the Vietnam War era, the RTAF was supplied with USAF-aid equipment. History Thailand's history of aviation began in January 1911, when a French pilot performed a flying demonstration over Bangkok. Prince Chakrabongse Bhuvanath, brother of King Vajiravudh, was in attendance and was greatly impressed, even accepting an invitation to fly aboard the plane. Chakrabongse arranged to send three army officers to France, who began aviation training at Vélizy-Villacoublay in July 1912. The officers became qualified aviators a year later, with one pursuing further training. In late 1913, the three new aviators returned to Thailand after arranging for the purchase of four Nieuport monoplanes and a Bréguet Aviation. The fledgling aviation section put on a successful demonstration in January 1914, gaining the support of the King. A permanent aviation group under the Army was established and an air base at Don Muang was designated. After Thailand entered World War I on the side of the Allies in July 1917, an expeditionary force of around 1,200 men was sent to France in June 1918. Among the expeditionary force were a total of 370 pilots and groundcrew, including more than 100 officers. The officers were sent to flight school at Istres and Avord, but many had to be retrained at Istres, Le Crotoy, La Chapelle-la-Reine, Biscarosse and Piox as they were deemed incapable of high altitude flight. Eventually, 95 pilots qualified as military aviators, and they few several operational sorties in the closing weeks of the war. The Thai aviators suffered no casualties nor scored any kills, but their extensive training meant Thailand entered the post-WWI period with one of the best equipped and trained air forces in Asia. In the 1930s, Thailand began to replace its ageing French planes with American materiel, purchasing more than 95 planes including the Boeing P-12E, Curtiss Hawks, and Vought Corsairs. The air force was formally separated into its own branch, the Royal Thai Air Force, in 1937. Five operational wings were also established in the reorganization. At the end of 1940, the RTAF once again entered combat, this time in a border conflict against French Indochina. The RTAF operated in