Military circles of Thailand

Thailand is divided into four military regions (or areas). Each region is subdivided into up to 10 districts. Army Region 1 covers central Thailand, while Region 2, 3 and 4 correspond to northeastern, northern and southern Thailand respectively.^[2] All key units are located at dedicated military forts, which are named after key monarchs or heroes.

Army Area 1 was established on 13 January 1911 as an amalgamation of three monthon-level units. At that time it was named Army 1^[3] There were two other armies, Army 2 and Army 3, located at Phitsanulok and Nakhon Ratchasima respectively. Army Area 1 controls Army Corps 1. It also supervises all military units in central Thailand, covering 9 army districts as follows.

Army 3, headquartered in Nakhon Ratchasima, was dissolved in 1927 due to economic depression. The unit was re-established by the royal decree of 1948 and named Army Area 2.^[4] It supervises 10 army districts, all of which are in northeastern Thailand. It also commands Army Corps 2. Its headquarters are at Fort Suranari, Nakhon Ratchasima.^[5]

Army 2, located in Phitsanulok, was reorganised in 1948 to form the Army Area 3.^[4] Its headquarters are at Fort King Naresuan the Great, Phitsanulok.^[6] It supervises Army Corp 3 and 10 army districts, all of which are from northern Thailand.

On 7 February 1925, Army Area 4 was established to supervise all military units in southern Thailand. Unlike other army areas, Army Area 4 does not have a satellite corp. Its headquarters are at Fort Vajiravudh, Nakhon Sri Thammarat.^[7]

This map shows subdivisions of the Royal Thai Army, in accordance with the 2015 ministerial regulation signed by Prayut Chan-o-cha.^[1] The country is split into four army areas, numbered 1 to 4. Each army area contains 6 to 10 army districts. Each district is numbered. The first digit refers to the army area in which the district is located. The second and third digits are a sequential number 1 to 10 (without 0). As a consequence, there are no district 10, 20, 30 and 40. All army districts are provincial-level military units de facto. Sometimes army districts are referred to as military circles due to ambiguity of the original Pali term.^{[n 1]}

In accordance with the by-law enacted in 2009,^[10] all army areas plan, manage, supervise and act as a chief in national security, peacekeeping and other roles according to the government policy. All army areas also

1. Secure all members of the Royal Family;
2. Actuate Royal-initiated projects (in collaboration with other bodies), and
3. Engage in Military operations other than war.

As subordinate units to the army areas, military districts have following roles^[1][11]

1. Govern local military forces, according to instructions and regulations by the Ministry of Defence;
2. Maintain peace in its area; supervise military courts, cases, witness protection and military prisons;
3. Recruit new members of the forces; oversee conscription and military summoning;
4. Support military units in its area;
5. Protect the internal security and national security according to the strategic plan;
6. Support the government in supporting Thai citizens;
7. Work closely with the Internal Security Operations Command local centres.

In 1911, Vajiravudh proposed that Siam (now Thailand) must have a modernised army system. He divided Siam into three regions, Army 1 (central and southern), Army 2 (northern) and Army 3 (northeastern). Each monthon (a collection of cities and settlements, similar to China today) has one division. All divisions in a region formed a regional army.^[12] In 1927, due to economic crisis, northeastern army and some military units were dissolved. The remaining armies were Armies 1 and 2, located at Bangkok and Ayutthaya respectively.^[5]

In 1948, during the Bhumibol Adulyadej's reign, Thailand was divided into 5 military districts in accordance with different regions: central, eastern, northeastern, northern and southern.^[13] Seventeen years later, the Royal Thai Army realised that the organisation was too bulky--there were too many provinces under supervision of an army district. The military government, led by Thanom Kittikachorn, proposed that the country be divided into three armies. Each armies were divided into districts^[14]

In 1990, the Royal Thai Army was reorganised into four army regions. Each region was divided into many army districts, each of which covered few provinces. Each military district was divided into military provinces (Thai: จังหวัดทหารบก). Some military provinces cover many civil provinces (Thai: จังหวัด) (such as Chiang Mai army province, covered Chiang Mai, Mae Hong Son and Lamphun), while others cover one (such as Nan army province, covered Nan only). As a superior unit to provinces, army district were located at large military bases in key provinces.^[15] In 2015, Prayut Chan-o-cha proposed that each military district should cover fewer provinces in order to make the chain of command more efficient and reduce the complexities of the military formation.^[1] This is particularly clear in northern and northeastern Thailand.

• Provinces of Thailand
• Monthon
• Royal Thai Army
• Military district
• Divisions of the United States Army -- Similar military subdivision system used in the United States