Military history of Thailand The military history of Thailand encompasses a thousand years of armed struggle , from wars of independence from the powerful Khmer Empire , through to struggles with her regional rivals of Burma and Vietnam and periods of tense standoff and conflict with the colonial empires of Britain and France . Thailand ' s military history , dominated by her centrality in the south - eastern Asian region , the significance of her far flung and often hostile terrain , and the changing nature of military technology , has had a decisive impact on the evolution of both Thailand and her neighbours as modern nation states . In the post - war era , Thailand ' s military relationship with the United States has seen her play an important role in both the Cold War and the recent War on Terror , whilst her military ' s involvement in domestic politics has brought frequent international attention . State formation and Siam ' s regional conflicts ( 1300 – 1826 ) . The Siamese military state emerged out of the disintegration in the 14th century of the once powerful Khmer Empire . Once a powerful military state centered on what is today termed Cambodia , the Khmer dominated the region through the use of irregular military led by captains owing personal loyalty to the Khmer warrior kings , and leading conscripted peasant s levied during the dry seasons . Primarily based around its infantry , the Khmer army was typically reinforced by war elephant s and later adopted ballista artillery from China . By the end of the period , indigenous revolts amongst Khmer territories in Siam and Vietnam , and external attack from the independent kingdom of Champa , sapped Khmer strength . After the sack of the Khmer capital Angkor Wat by Champa forces in 1178 - 9 , Khmer ' s ability to control its wider territories diminished rapidly . The first Siamese kingdom to gain independence , Sukhothai , soon joined to the newly independent Ayutthaya kingdom in 1350 . After 1352 Ayutthaya became the main rival to the failing Khmer empire , leading to Ayutthayan conquest of the Khmer in 1431 . The subsequent years saw constant warfare as numerous states attempted to exploit the collapse of Khmer hegemony . As none of the parties in the region possessed a technological advantage , the outcome of battles was usually determined by the size of the armies . The use of war elephants continued , with some battles seeing personal combat between commanders on elephants . In 1592 , Nanda Bayin king of Toungoo ordered his son Mingyi Swa to attack Ayutthaya Naresuan encamped his armies at Yuddhahatthi . The Burmese then arrived , leading to the Battle of Yuddhahatthi . Naresuan can killed Mingyi Swa during the battle . After that Burmese army withdrew from Ayutthaya . in 1599 Naresuan also occupied city of Pegu but Minye Thihathu Viceroy of Toungoo took Nanda Bayin and left for Toungoo . When Naresuan reached Pegu , what he found was only the city ruins . He requested Toungoo to sent Nanda Bayin back to him but Minye Thihathu refused . After each victorious campaign , Ayutthaya carried away a number of conquered people to its own territory , where they were assimilated and added to the labor force . To the south , Autthaya easily achieved domination over the outlying Malay states . To the north , however , the kingdom of Burma posed a potential military threat to the Siamese kingdom . Although frequently split and divided in the 16th century , during periods of unity Burma could , and did , defeat Ayuttahaya in battle , such as in 1564 and 1569 . What followed was another prolonged period of Burmese disunity . During Ayutthayan King Narai ' s reign , conflicts with England ' s East India Company led to the Siam – England war of 1687 . The English were subsequently banned from Siam until their defeat of Burma in the First Anglo - Burmese War ( 1824 – 1826 ) . A century after Siam repelled the English Company , a reunified Burma successfully invaded Ayutthaya again in 1767 , this time burning the capital and temporarily dividing the country . General , later King , Taksin assumed power and defeated the Burmese at the battle of Pho Sam Ton Camp later in 1767 . With Chinese political support , Taksin fought several campaigns against Vietnam , wresting Cambodia from Vietnamese control in 1779 . In the north , Taksin ' s forces freed the kingdom of Lanna from Burmese control , creating an important buffer zone , and conquered the Laotian kingdoms in 1778 . Ultimately , internal political dissent , in part fed by concerns over Chinese influence , brought the deposition of Taksin and the establishment of General Chakri as Rama I in 1782 and the founding of the Rattanakosin Kingdom with its new capital city at Bangkok . Military competition for regional hegemony continued , with continued Siamese military operations to maintain their control over the kingdom of Cambodia , and Siamese support for the removal of the hostile Tây Sơn Dynasty in Vietnam with the initially compliant ruler of Nguyễn Ánh . In later years , the Vietnamese emperor was less cooperative , supporting a Cambodian rebellion against Siamese authority and placing a Vietnamese garrison in Phnom Penh , the Cambodian capital , for several years . Conflict with Burma was renewed in the two campaigns of the Burmo - Siamese war ( 1785 - 6 ) , seeing initial Burmese successes in both years turned around by decisive Siamese victories . The accession of Rama II in 1809 saw a final Burmese invasion , the Thalang campaign , attempting to take advantage of the succession of power . Despite the destruction of Thalang , Rama ' s ultimate victory affirmed Siamese relative military superiority against Burma , and this conflict was to represent the final invasion of Siamese territory by Burma . Siam and the European military threat ( 1826 – 1932 ) . The British victories over Burma in 1826 set the stage for a century in which the military history of Thailand was to be dominated by the threat of European colonialism . Initially , however , Siamese concern remained focused on its traditional rivals of Burma and Vietnam . Siam intervened in support of Britain against Burma in 1826 , but her lackluster performance inspired Chao Anouvong ' s surprise attack on Korat . Lady Mo ' s resistance established her as a cultural heroine , and General Bodindecha ' s victory two years later established him as a major figure in Thai military history . His successful campaign in the Siamese – Vietnamese War ( 1841 – 1845 ) reaffirmed Siamese power over Cambodia . In 1849 , weakening Burmese power encouraged revolt amongst the Burmese controlled Shan states of Kengtung and Chiang Hung . Chiang Hung repeatedly sought Siamese support , and ultimately Siam responded with the initial despatch of forces in 1852 . Both armies found difficulties campaigning in the northern mountainous highlands , and it took until 1855 before the Siamese finally reached Kengtung : though with great difficulty and the exhaustion of Siamese resources ultimately resulted in their retreat . These wars continued to be fought in the traditional mode , with war elephants continued to be deployed in the field carrying light artillery during the period , often being a decisive factor in battle . Meanwhile , the visible military weaknesses of China in the First and Second Opium War s with Britain and later France between the 1830s and 1860s encouraged Siam to reject Chinese suzerainty in the 1850s . Siam , however , was under military and trade pressure itself from the European powers , and as King Rama III reportedly said on his deathbed in 1851 : " " We will have no more wars with Burma and Vietnam . We will have them only with the West . " " Under Napoleon III , France escalated the military pressure on Siam from the east ; France ' s naval interventions in Vietnam in the 1840s gave way to a concerted imperial campaign . Saigon fell in 1859 , with French ascendency in Vietnam being confirmed in 1874 . France took Cambodia in 1863 , combining it with Vietnam to form the colony of Indochina in 1887 . From the south , Britain ' s involvement in the Larut and Klang wars of the 1870s increased both its grip over and political investment in the Malay states . From the north , Britain , triumphant in the Second Anglo - Burmese War of 1852 , ultimately concluded its conquest of Burma in the Third Anglo - Burmese War and had incorporated the kingdom of Burma into the British Raj by 1886 . The European military dominance was driven largely by the dominance of European naval power , coal powered vessels , increasingly iron clad , eclipsing the local brown water navies . Nonetheless , European campaigns remained limited by the difficulties and costs of military logistics and the climate , especially the threat of malaria . Siam ' s response under King Mongkut was to commence a wide programme of reform in the Western model , which including the Siam military . The Royal Thai Army traces its origins as a standing force to Mongkut ' s creation of the Royal Siamese Army as a standing force in the European tradition in 1852 . By 1887 , Siam had permanent military commands , again in the European fashion , and by the end of the century , Siam had also acquired a Royal Navy from 1875 with a Danish naval reserve officer ; Andreas du Plessis de Richelieu in charge and after his deprture in 1902 with the Thai noble title Phraya Chonlayutthayothin ( Thai : พระยาชลยุทธโยธินทร์ ) under the reforms of Admiral Prince Abhakara Kiartiwongse . Siam ' s increasing focus on centralised military force to deter European invasion came at the cost of the former decentralised military and political arrangements , beginning a trend towards centralised military power that would continue into the 20th - century Thai history . Despite the growing Siamese military strength , Siam ' s independence during much of the late 19th century on the ongoing rivalry between Britain and France across the region , especially in the search for lucrative trade routes into the Chinese hinterlands . By developing an increasing sophisticated military force and playing one colonial rival off against another , successive Siamese monarchs were able to maintain an uneasy truce until the 1890s . The closing act of this struggle was the French occupation of eastern Thai territory in the Franco - Siamese war of 1893 , which paved the way for an uneasy peace between Siam and France in the region for the next forty years . French Indochina ' s Governor - General had sent an envoy to Bangkok to bring Laos under French rule , backed by the threat of French military force . The Siamese government , mistakenly believing that they would be supported by the British , refused to concede their territories east of the Mekong river and instead reinforced their military and administrative presence there . Spurred on by the expulsion of French merchants on suspicion of opium smuggling , and the suicide of a French diplomat returning from Siam , French took the Siamese refusal to concede its eastern territories as a case for war . In 1893 the French ordered their navy to sail up the Chao Phraya river towards Bangkok . With their guns now trained on the Siamese royal palace , the French delivered an ultimatum to the Siamese to hand over the disputed territories and to pay indemnities for the fighting so far . When Siam did not immediately comply unconditionally to the ultimatum , the French blockaded the Siamese coast . Unable to respond at sea or on land , in the end the Siamese submitted fully to the French conditions , finding no support from the British . The conflict led to the signature of the Franco - Siamese Treaty shortly afterwards , in which the Siamese conceded Laos to France , an act that led to the significant expansion of French Indochina . In 1904 the French and the British put aside their differences with the Entente Cordiale , which ended their dispute over routes in southern Asia and also removed the Siamese option for using one colonial power as military protection against another . Meanwhile , the Anglo - Siamese Treaty of 1909 produced a compromise , largely in Britain ' s favour , between Britain and Siam over the disputed territories in the north of Malaya . Siam ' s next conflict was its two - year involvement in the First World War , fighting on the side of the Entente Powers , the only independent Asian nation with land forces in Europe during the Great War . The result of this intervention in 1917 was the revision or complete cancellation of some of the unequal trade treaties with the United States , France and the British Empire - but not the return of the bulk of the disputed Siamese territories lost in the previous century . Thailand , the Second World War and Japanese occupation ( 1932 – 45 ) . For Thailand — renamed from Siam in 1939 — the Second World War involved both the bilateral struggle between the Axis and Allied forces in the region but also the regional struggle across south - east Asia between historic rivals . Like other regional actors , Thailand - under military rule following the coup of 1932 and led by Prime Minister Major - General Plaek Pibulsonggram ( popularly known as " Phibun " ) - was to exploit the changes in power caused by the fall of France and the expansion of Japan to attempt to off - set the losses of the previous century . Thailand ' s considerable investment in her army , based on a mixture of British and German equipment , and her airforce - a blend of Japanese and American aircraft - was about to be put to use . The conflict fell into three broad phases . During the initial phase following the fall of France in 1940 and the establishment of Japanese bases in France ' s Far Eastern colonial territories , Thailand opened up an air offensive along the Mekong frontier , attacking Vientiane , Sisophon , and Battambang with relative impunity . In early January 1941 , the Thai Army launched a land offensive , swiftly taking Laos whilst entering into a more challenging battle for Cambodia where the pursuit of the French units proved more difficult . At sea , however , the heavier forces of the French navy quickly achieved dominance , winning skirmishes at Ko Chang , followed by the French victory at the Battle of Ko Chang . The Japanese mediated the conflict , and a general armistice was held January 28 , followed by a peace treaty signed in Tokyo on May 9 , with the French being coerced by the Japanese into relinquishing their hold on the disputed territories . During the second phase , Japan took advantage of the weakening British hold on the region to invade Siam , seeing the country as an obstacle on the route south to British held Malaya and its vital oil supplies , and north - west to Burma . On December 8 , 1941 , after several hours of minimal fighting between Siamese and Japanese troops , Thailand acceded to Japanese demands for access . Later that month Phibun signed a mutual offensive - defensive alliance pact with Japan giving the Japanese full access to Thai railways , roads , airfields , naval bases , warehouses , communications systems , and barracks . With Japanese support , Thailand annexed those former possessions in northern Malaya it had been unable to acquire under the 1909 treaty , and conducted a campaign against its former allies in the Shan state s of Burma along its northern frontier . By the final stages of the war , however , the weakening position of Japan across the region and the Japanese requisition of supplies and materiel reduced the military benefits to Siam , turning an unequal alliance into an increasingly obvious occupation . Allied airpower achieved superiority over the country , bombing Bangkok and other targets . The sympathies of the civilian political elite , moved perceptibly against the Phibun regime and the military , forcing the Prime Minister from office in June 1944 . With the fall of Japan , France and Britain insisted on the return of those lands annexed by Siam during the conflict , returning the situation to the situation " ante bellum " . The conflict highlighted the new importance of airpower across the region , for example the use of dive bomber s against French troops in 1941 or the use of air reconnaissance in the northern mountains . It had also highlighted the importance of well trained pilots to effective airwar . Ultimately , the conflict emphasised the challenges of logistics across often impassable terrain , which generated expensive military campaigns - a feature to reemerge in the post - war period during the conflicts in French Indochina . Thailand and regional Communism ( 1945 – 90 ) . Thailand ' s military history in the post - war period was dominated by the growth of Communism across the region , which rapidly became one of the fault lines in the Cold War . Thailand ' s successive governments found that the Communist bloc in south - east Asia largely consisted of their historical military rivals , and were increasing drawn both into the regional struggle and into having to deal with Communist insurgency at home . Thailand ' s postwar leaders were mainly traditionalists , seeking to restore the prestige of the monarchy and to defeat the growth of Communism , which was closely associated with Thailand ' s traditional enemies , the Vietnamese - now in open revolt against the French . Following Thailand ' s participation in the Korean War , and with the steady growth of U . S . involvement in the region , Thailand formally become a U . S . ally in 1954 with the formation of the Southeast Asia Treaty Organization ( SEATO ) . Whilst the war in Indochina was being fought between the Vietnamese and the French , Thailand - disliking both her old rivals equally - initially refrained from entering the conflict , but once it became a war between the U . S . and the Vietnamese Communists , Thailand committed itself strongly to the U . S . side . Thailand concluded a secret military agreement with the U . S . in 1961 , and in 1963 openly allowed the use of their territories as air bases and troop bases for U . S . forces before finally sending her own troops to Vietnam . Thailand was however more involved with the secret war and covert operations in Laos from 1964 to 1972 . The Vietnamese retaliated by supporting the Communist Party of Thailand ' s insurgency in various parts of the country . By 1975 relations between Bangkok and Washington had soured ; eventually all U . S . military personnel and bases were forced to withdraw and direct Thai involvement in the conflict came to an end . The Communist victory in Vietnam further emboldened the Communist movement within Thailand . After the Thammasat University massacre in 1976 and the repressive policies of Tanin Kraivixien sympathies for the movement increased , and by the late 1970s it was estimated that the movement had about 12 , 000 armed insurgents , mostly based in the northeast along the Laotian - Khmer border . Counter - insurgency campaigns by the Thai military meant that by the 1980s insurgent activities had been largely defeated . Meanwhile , the Vietnamese invasion of Cambodia in 1978 to remove the Pol Pot regime - tacitly supported by Thailand and China - brought the Vietnamese - Thailand conflict up to the Thai border , resulting in small border raids and incursions by Vietnamese against the remaining Khmer Rouge camps inside Thai territory , that lasted until 1988 . Thailand , meanwhile , with U . S . support sponsored the creation of the Khmer People ' s National Liberation Front , which operated against the new Vietnamese - backed Cambodian government from 1979 onwards from bases inside Thailand . Similar small skirmishes emerged along the Thai - Laotian border in 1987 - 1988 . Post communist period ( 1990 onwards ) . The last twenty years of Thailand ' s military history has been dominated less by the threat of external attack , but by the role of the Thai military in internal politics . For most of the 1980s , Thailand was ruled by prime minister Prem Tinsulanonda , a democratically - inclined leader who restored parliamentary politics . Thereafter the country remained a democracy apart from a brief period of military rule from 1991 to 1992 , until , in 2006 mass protests against the Thai Rak Thai party ' s alleged corruption prompted the military to stage a coup d ' état . A general election in December 2007 restored a civilian government , but the legacy of the Thai military ' s frequent involvement in domestic politics remains . Meanwhile , the long - running southern insurgency , waged by the ethnic Malay s and Islamic rebels in the three southern provinces of Yala , Pattani and Narathiwat intensified in 2004 , with attacks on ethnic Thai civilians from the insurgents escalating . The Royal Thai Armed Forces in turn responded in force . Casualties currently stands at 155 Thai military personnel killed against 1 , 600 insurgents killed and about 1 , 500 captured , against the backdrop of about 2 , 729 civilian casualties . Strong U . S . military support for Thailand under President Bush , as part of the U . S . War on Terror , assisted the Thai military in this counter - insurgency role , although discussions continue in the Royal Thai Government as to the role of the military , vice civilians , in the leadership of this campaign . U . S . Air force units have also been permitted to use Thai air bases once more , flying missions over Afghanistan and Iraq in 2001 and 2003 respectively . The Thai military maintains strong regional relations under the Association of South - Eastern Asian Nations ( ASEAN ) organisation , illustrated by the annual Cobra Gold exercises , the latest in 2009 involving 12 , 000 soldiers from Thailand , the U . S . , Japan , Singapore and Indonesia , characterised as the largest such exercise in south - east Asia . This association , bringing together many former enemies , plays an important part in ensuring ongoing peace and stability across the region . Thai troops have been controversially used to attempt to quell the 2010 Thai political protests , resulting in numerous civilian deaths .