Thailand’s military affairs came into existence at the same time when the Kingdom of Thailand was established. They have subsequently developed from Sukhothai period through Rattanakosin era.
In the reign of King Chulalongkorn (King Rama the Fifth), our great beloved King systemised the Thai military for the purpose of defending, maintaining Thailand’s freedom, integrity and sovereignty and keeping abreast with civilized countries. The King brought the army and the navy under the command of His Royal Highness the Crown Prince (Prince Mahavajirunahidh).
On April 8, 1887, the King issued a decree to establish the War Department, during the period, the Thai military affairs were extensively developed and modernized in pursuit of those civilized countries. Later on, April 1, 1890, the War Department was upgraded to the War Ministry with the Army and the Navy under its command.
In the reign of King Vajiravudh (King Rama the Sixth), the War Ministry was changed into the Ministry of Defence. Its responsibility was only for the army as the navy was separated to become the Navy Ministry.
After World War I, the Navy Ministry rejoined to the Ministry of Defence on November 8, 1931 and the Air Force was established on April 9, 1937. Since then, there have been three armed services in the Ministry of Defence, namely Army, Navy and Air Force