Thailand declares war on the Allies

At noon on 25 January 1942 a declaration came into force in which the government of Thailand announced that it was in a state of war with Great Britain and the United States. It was the last step along a path the country had travelled in less than seven weeks: from a few hours of resistance to the Japanese invasion on 8 December 1941, through consent to the passage of Japanese troops, to the alliance with Japan concluded on 21 December. The decision was taken by the government of Field Marshal Plaek Phibunsongkhram, known as Phibun. London took note of the declaration of war and responded in kind. Washington never received it at all, because the Thai minister in the United States refused to deliver the document. This difference shaped Thailand’s fate until the end of the war and beyond.

From passage to alliance

After the ceasefire of 8 December, Japanese troops passed through Thailand into Malaya and towards the Burmese frontier, and Thai airfields, ports and railways became the rear base for the entire Japanese offensive in South-East Asia. The treaty of alliance signed in Bangkok on 21 December 1941 bound both sides to mutual political, economic and military assistance. A secret protocol promised Thailand help in recovering the lands it had lost to the British in the nineteenth and early twentieth centuries – that is, part of the Shan States in Burma and the sultanates of northern Malaya. A year earlier, thanks to Japanese mediation and the Treaty of Tokyo, Phibun had already recovered the lands taken from Thailand by France. Further territorial gains tempted him all the more because Japan’s victories in the first weeks of the war – from Pearl Harbor to the sinking of the British capital ships off Kuantan and the rapid advance through Malaya – seemed to settle the outcome of the war in Asia.

For several weeks, however, Thailand formally remained a country allied to Japan but not at war with its enemies. British air raids put an end to this ambiguity. On the night of 7–8 January 1942 a few RAF Bristol Blenheim bombers flying from airfields near Rangoon attacked military targets in Bangkok, including Hua Lamphong railway station; bombs also fell on the Chinese quarter of Yaowarat, where fires broke out. The British struck at the capital because Japanese transports to Burma and Malaya passed through it. The next raid came on the night of 24–25 January, when eight Blenheims attacked military installations in the government quarter, near the Ananta Samakhom Throne Hall, where parliament sat; according to Thai figures, three sentries were killed. By noon the next day Thailand was at war.

The declaration

The government justified its decision precisely by the British and American attacks on Thai territory, presenting them as hostile acts against a state that wished only to defend its independence. The declaration of war was announced on the radio, and the Thai Foreign Ministry notified the consul of Switzerland in Bangkok, which represented the interests of the Allied states. The Thai minister in London handed the declaration to the British government.

The reigning king, Ananda Mahidol, was a minor living in Switzerland, so acts of state were signed on his behalf by a regency council. Since December 1941 one of its members had been Pridi Banomyong, Phibun’s former comrade from the revolution of 1932, who opposed the rapprochement with Japan and had for that reason been removed from the government. According to Thai accounts, Pridi was not in Bangkok when the declaration was put before the council, and the document was signed only by the other regents. This absence, whether accidental or deliberate, was later to serve as one of the arguments that the declaration of war had not expressed the will of the state.

Historians assess Phibun’s motives in different ways. Some emphasise pressure from Japan, which wanted Thailand as a fighting ally and not merely as a country tolerating the presence of its troops. Others, such as the Japanese scholar Kenjirō Ichikawa, point out that Phibun himself was counting on a Japanese victory and wanted to recover the border territories of Burma and Malaya at Japan’s side. Declaring war also allowed him to present the alliance with Japan to his compatriots as a choice rather than the result of defeat, and strengthened his position as the leader of a nation regaining its former territories. According to some historians, he also counted on being able to back out of the decision should the Allies win. Either way, Thailand became the only independent state in South-East Asia fighting on Japan’s side.

Seni Pramoj refuses

Thailand’s minister in Washington since 1940 had been Seni Pramoj, an aristocrat, an Oxford-educated lawyer and a great-grandson of King Rama II. As early as 8 December 1941, after a conversation with Secretary of State Cordell Hull, Seni and the entire legation staff decided to side with the Allies. Seni blamed the capitulation on pro-Japanese circles in the government and proposed that Thais living in America form a centre of “truly patriotic, freedom-loving Thais” for as long as the government in Bangkok remained in Japanese hands.

When the declaration of 25 January arrived, Seni refused to deliver it to the American government. He took the view that a document issued under Japanese occupation did not express the will of the Thai people. The State Department decided to behave as if Seni still represented Thailand, which allowed him to draw on Thai assets frozen in the United States. In a memorandum passed to the British on 7 February 1942, the State Department explained its position: the United States would not declare war on Thailand, but would treat Thai forces as enemies if they went into action alongside the Japanese, and would treat Thailand itself, for the purposes of economic warfare, as enemy-occupied territory. The United States never declared war on Thailand.

Seni soon began organising the Seri Thai, or “Free Thai”, movement. Its recruits were above all Thai students at American universities – Harvard, the Massachusetts Institute of Technology, Cornell – who had refused to return home after the declaration of war. In time they were trained by the American Office of Strategic Services (OSS), set up in June 1942, while a similar group among Thais in Britain was prepared by the British Special Operations Executive (SOE). In Thailand itself the underground network was directed by the regent Pridi.

The response of London and the Dominions

Great Britain received the declaration differently from the Americans. It announced that a state of war had existed between it and Thailand since 25 January 1942, and from then on treated the country as an enemy state. For London the matter was not merely a legal one: the Japanese were attacking Malaya and Burma from Thai territory, and the Thai claims concerned lands under British rule. According to lists of declarations of war, New Zealand and the Union of South Africa followed London’s lead and recognised a state of war with Thailand on the same day. Australia did so by a separate act only on 2 March 1942, through the intermediary of Switzerland.

Thailand thus found itself in a curious position: it was at war with Great Britain and some of the Dominions, but not with the United States, although it had itself declared war on both powers. In 1942 this asymmetry had no practical significance, since none of the Allies was in a position to threaten Thailand, but the Atlantic Charter, proclaimed half a year earlier, and the Declaration by United Nations, signed on 1 January 1942, gave the Americans grounds for treating Thailand as a victim of Japanese aggression rather than its accomplice.

Place in the war

The declaration of war brought Phibun what he had hoped for, but only for a short time. In May 1942 the Thai Phayap Army entered the Shan States of Burma and on 27 May took Kengtung, driving out a Chinese division. In 1943 Japan formally handed over to Thailand part of the Shan States and four sultanates of northern Malaya. At the same time more and more Japanese troops were stationed in the country, behaving like occupiers, and from December 1942 Bangkok was bombed by American aircraft from India, even though the United States was formally not at war with Thailand. Inflation, requisitions and air raids undermined Phibun’s position, and in July 1944 he was forced to resign.

After Japan’s surrender the regent Pridi proclaimed that the declaration of war of 25 January 1942 was null and void, since it had been contrary to the constitution and to the will of the nation. The United States accepted this interpretation and never concluded a peace treaty with Thailand, because in its eyes there had been no war. Seni Pramoj returned to Bangkok in September 1945 and became prime minister. Great Britain, which regarded itself as a party to the war, demanded concessions, above all deliveries of rice for its colonies, and only on 1 January 1946, in Singapore, signed an agreement with Thailand ending the state of war; Australia concluded a separate treaty in April 1946. Thailand returned the lands it had gained with Japan’s help, and in December 1946 it was admitted to the United Nations.

The decision of 25 January 1942, taken at the moment of Japan’s greatest triumphs, thus proved less costly for Thailand than it might have been. The country escaped the fate of a defeated enemy above all because its minister in Washington did not deliver the declaration, and because the Free Thai movement gave the Allies reason to see Thailand after the war as a victim rather than an ally of Japan. Phibun, tried after the war for collaboration with Japan and released, became prime minister again in 1948.