The B-29 raid on Bangkok

At the beginning of January 1945, American B-29 Superfortress bombers of XX Bomber Command took off from airfields around Kharagpur in Bengal, about a hundred kilometres west of Calcutta, and flew to Bangkok. Their target was the Rama VI Bridge over the Chao Phraya (Menam) river in the north of the city – the only rail crossing of the river, linking the northern line with the southern line that led towards Malaya and to the railway to Burma. The bombers hit the bridge and its approaches, putting it out of use for a time.

Popular chronicles of the war describe the raid as an attack by 46 bombers from the Calcutta area on a railway bridge near Bangkok and other targets in the vicinity. The overall picture is accurate, but the details need refining. According to the American official history of the air force (Wesley F. Craven and James L. Cate, The Army Air Forces in World War II), 49 bombers were prepared for the operation and 44 reached the target; the figure of 46 probably derives from a different way of counting the aircraft that attacked the primary and secondary targets. The same history dates the attack on the bridge to 3 January, as do Thai accounts of the defence of the capital – though in some tallies the mission appears under the date of 2 January. The bridge did not stand “near Bangkok” but within what is today the metropolis, in the Bang Sue district, about 13 kilometres from the main railway station.

Bombers without China

XX Bomber Command had arrived in India in the spring of 1944 to bomb Japan from forward airfields in Sichuan under the Matterhorn plan – the campaign of the B-29 raids from China. Every sortie over Kyushu, however, required many supply flights over the Himalayas, and the Japanese Operation Ichi-Go, launched in April 1944, threatened the forward bases of the American air force in China and made supply even more difficult. When the first B-29s of XXI Bomber Command landed in the Marianas in the autumn of 1944, the point of keeping the bases in China began to disappear.

In January 1945 the command finally abandoned the airfields around Chengdu – the last mission from there was flown in the middle of the month against Taiwan – and concentrated on targets in South-East Asia within reach of India: ports and railways in Burma, Thailand and Indochina, and the docks of Singapore, which the bombers had been attacking since November, beginning with the raid on Singapore. This served to support the British and Indian forces in Burma, which came under Admiral Louis Mountbatten’s South East Asia Command. Major General Curtis LeMay, who had been in command in India, moved to the Marianas in the second half of January, and Brigadier General Roger Ramey took over the command at Kharagpur.

The bridge and the railway

The Rama VI Bridge, named in honour of King Vajiravudh (Rama VI), was built from 1922 and opened on 1 January 1927. It was 441 metres long with five truss spans, and carried both rail and road traffic. Through it ran the traffic from the north of the country and from Bangkok to the south – towards Malaya and to the station at Nong Pladuk, where the Burma Railway began.

The Japanese built this line of more than 400 kilometres from Thailand to Burma in 1942–1943 to supply their army in Burma without relying on the sea route, which was increasingly threatened by Allied submarines. Some 60,000 Allied prisoners of war – British, Australian, Dutch and American – worked on it, along with, according to various estimates, between 180,000 and more than 250,000 Asian labourers, mainly from Burma, Malaya and the Dutch East Indies. Hunger, disease and exhaustion killed, according to the most frequently cited figures, some 12,000–13,000 prisoners and several tens of thousands – in some estimates nearly 100,000 – Asian labourers. From the autumn of 1944 Allied aircraft regularly attacked bridges and stations on the line, including the bridges over the Mae Klong near Kanchanaburi, later famous from the film about the bridge on the River Kwai. Prisoners of war also died in the raids on the railway and the camps.

The raid

Bangkok was not the original target. On 30 December 1944 a reconnaissance B-29 spotted a Japanese naval force with two battleships off Cape Saint-Jacques in Indochina (today Vũng Tàu). LeMay ordered 49 bombers to be loaded with eight 1,000-pound (about 450 kg) bombs each, but before the aircraft took off the navy reported that the ships had sailed. According to Craven and Cate, an attempt to send the same aircraft against the railway junction at Mandalay was called off because of a bad weather forecast; LeMay therefore had the bomb fuzes changed and sent the bombers against the bridge in Bangkok, which had already been the target of earlier Allied raids.

The bombers arrived in several waves. According to the American official history, 44 aircraft reached the target and scored a direct hit on the bridge, several near misses and numerous hits on the approaches, putting the crossing out of use for a time. The rest attacked secondary targets. According to Thai aviation historians, Nakajima Ki-43 fighters of the Thai 15th Fighter Squadron (the Capital Defence Squadron) from Don Mueang airfield flew eleven sorties during the raid, while a few older biplanes could not even catch up with the bombers. According to the same accounts, the airman Dawee Chullasapya, who was connected with the Free Thai movement, copied the gun-camera photographs from the Thai fighters and secretly passed them to American intelligence.

Thailand between Japan and the Allies

Thailand was not an occupied country in the strict sense. On 8 December 1941, after a few hours of resistance, the government of Field Marshal Plaek Phibunsongkhram agreed to let Japanese troops pass through – the background to the Japanese invasion of Thailand – and in January 1942 it declared war on Britain and the United States. Washington did not recognise the declaration, because the ambassador, Seni Pramoj, refused to deliver it and organised the Free Thai movement (Seri Thai) in the United States. Bangkok was thus at once the capital of a formally sovereign ally of Japan and an important Japanese supply hub for the Burma front.

In July 1944, after the fall of Saipan and the Japanese defeat at Imphal (the end of the Japanese invasion of India), parliament removed Phibunsongkhram from power. Khuang Aphaiwong became prime minister, and the regent, Pridi Banomyong, the de facto leader of the underground. The domestic Free Thai network worked with the American OSS and the British SOE, received air drops of arms and agents, passed on intelligence and prepared a rising against the Japanese – which the Allies, especially Mountbatten, advised against launching prematurely. The bombing therefore had a twofold aim: to destroy Japanese communications and at the same time to convince the Thais that continuing to stand by Japan was costly.

The raids on Bangkok

American B-24 Liberator bombers of the Tenth Air Force based in India had been attacking Bangkok since December 1942 – the refinery, the port of Khlong Toei, Hua Lamphong station, the arsenal and power stations. After a pause the raids resumed in 1943, and in 1944 they became regular; besides the Americans, RAF Liberators also bombed targets in Thailand. This city was also where the combat history of the B-29 began: on 5 June 1944 XX Bomber Command attacked the Makkasan railway workshops in Bangkok. In November 1944 several dozen B-29s appeared over the city; according to Thai accounts, the Thai pilot Therdsak Worrasap shot one of them down on that occasion, being shot down himself.

The raids destroyed tracks, stations and wharves, but also hit the densely built-up districts around the targets. The number of civilian victims of all the raids on Bangkok is not known exactly, and estimates vary widely; some of the inhabitants left the city.

The January attack did not settle the matter of the bridge. In February 1945 the B-29s returned to Bangkok: according to the official history, 58 of the 64 aircraft dispatched bombed the bridge in small formations, scoring at least four direct hits. The bombs severed both top chords of the truss, brought down most of the central span and destroyed the north-eastern approach – Thai sources date the collapse of the central span to 7 February 1945. The bridge remained impassable until the end of the war; it was rebuilt only in 1950–1953 and reopened on 12 December 1953. From the spring of 1945 it was mainly RAF Liberators and American fighters that operated over Thailand – the latter attacking Don Mueang airfield in April – because the B-29s had been moved to the Marianas.

Place in the war

The raid on the Rama VI Bridge was one of many actions by which Allied air power, in the last year of the war, cut Japanese lines of communication in South-East Asia. Severing the crossing of the Chao Phraya hampered the movement of supplies from Bangkok to the south and to the Burma Railway just as General William Slim’s Fourteenth Army was approaching central Burma and the Japanese army in Burma was beginning to waver. In March 1945 the 58th Bombardment Wing left India and joined XXI Bomber Command in the Marianas – the B-29s’ part in the war in South-East Asia was over, and their place was taken by lighter aircraft of the RAF and the Tenth Air Force.

For Thailand the raids were part of the road out of the war on the losing side without suffering the fate of a defeated enemy. After Japan’s surrender, the regent Pridi Banomyong proclaimed on 16 August 1945 that the declaration of war of 1942 had been null and void. The United States, which had never regarded it as binding, backed the Thais, while Britain in January 1946 imposed an agreement under which deliveries of rice served as a form of reparations. British and Indian troops entered Bangkok and disarmed and repatriated the Japanese. The memory of the Burma Railway and its victims has survived above all at Kanchanaburi, home to the war cemeteries of Allied prisoners of war.