Bombing of Bangkok in World War II

Bangkok was bombed by both the Japanese and Allies during World War II. It was also the target for the first combat mission by Boeing B-29 Superfortresses in June 1944.

Japanese air attacks
Military targets at and near Bangkok were first bombed by 3rd Air Group's (第三航空隊) Mitsubishi Ki-30's of the 31st Sentai under Lt Col Hayashi Junji as part of the Japanese invasion of Thailand. Prior to the start of the invasion fighters from the 77th Sentai and bombers of the 31st Sentai moved to Siem Reap close to the Thai border. On the morning of December 8, 1941, they were ordered to attack Aran Pradet airfield near Bangkok. Nine 31st Sentai bombers, escorted by 11 Ki-27s of the 77th Sentai led by Japanese air ace Major Yoshio Hirose (広瀬 吉雄), headed for Bangkok. As they approached they were intercepted by three Thai Air Force Hawk III fighters from 43 Squadron. These fighters were flown by Flight Lieutenant Chin Chiramaneemai, Flight Lieutenant Chai Sunthornsing and Flying Officer Sarit Potivetchagul and were based at Watana Nakorn airfield in Prachinburi province. Major Hirose, Lieutenant Yoshiro Kuwabara and Lieutenant Tsuguo Kojima shot down all three planes. This was the only bombing raid during the Japanese invasion of Thailand because the Thai government acceded to Japan's demands by 1:00 pm that same day. An alliance was signed between Japan and Thailand on December 21, 1941. On January 25, 1942, the Thai government declared war on the United States and the United Kingdom.

Initial British and American air raids
Allied bombing raids on the Thai capital city of Bangkok began before Thailand had declared war because the Empire of Japan was using Thailand as a staging post for its invasions of both Malaya and Burma with the agreement of the Thai government. The first raid came on January 7, 1942, when Royal Air Force (RAF) aircraft flying from Rangoon, attacked military targets in the city. The American Volunteer Group together with seven No. 113 Squadron RAF and three No. 45 Squadron RAF Blenheim bombers, were involved in the first raid. No. 113 Squadron's planes were piloted by No. 60 Squadron's air crew. The second night raid was carried out with 8 Blenheims on 24-25 January and also included No. 60 Squadron RAF aircrew. A final raid was made three days later by four Blenheims. This was the last raid by Blenheims until May or June 1945.

After Rangoon fell to the Japanese on March 7, heavy bombers, such as RAF and American Tenth Air Force B-24s, based in India and China attacked Thailand. The raids were carried out because Bangkok was a command centre for the Japanese on the South East Asian front. RAF and USAAF bombers carried out these raids as part of the Pacific campaigns. The bombers targeted installations useful to the occupying Japanese military, but the raids were also intended to pressure the government of Thai military strongman Plaek Pibulsongkram to abandon his alliance with Imperial Japan. The major targets were the newly completed Port of Bangkok and the Thai railway system. Raids by RAF, USAAF, and other Allied air forces continued with growing intensity from India and, after the liberation of Rangoon on May 3, 1945, from Rangoon up until the end of the war in August that year. Blenheim bombers and Mustangs operated out of Rangoon against Bangkok in this later phase of the bombing.

First B-29 Superfortress combat mission
In its first combat mission, the American B-29 Superfortress was used by the XX Bomber Command's 58th Air Division to strike targets in Bangkok, before it was deployed against the Japanese home islands. The decision for using the B-29s to bomb Bangkok dated back to 1943 and was mentioned in a communicate between US President Franklin D. Roosevelt and British Prime Minister Winston Churchill in which Roosevelt suggested that they be used to bomb the port and railways.

On 5 June 1944, 98 B-29s led by the 58th's commander, General LaVerne Saunders, flew out from airfields in India to attack the Makasan railway yards in Bangkok. The raid was the longest distance mission to that date in the war. It was a 2,261-mile round trip. Only 77 of the B-29s made it to Bangkok, with 21 having had to return home because of various engine problems. Arriving at the Thai capital at about 11:00 am, the bombers found the target obscured by bad weather which in turn caused an element of confusion in the attack. The B-29s were meant to have dropped their bombs from between 22–25,000 feet altitude but instead did so from between 17–27,000 feet. Only 18 bombs hit their intended targets. The others destroyed a Japanese military hospital and damaged the Japanese secret police headquarters. On the return leg, 42 B-29s had to divert to other airfields because of a lack of fuel and five crashed on landing, although none were lost to enemy fire. Further raids were carried out by the Superfortresses against strategic targets in Bangkok.

Temporary British occupation
At the end of hostilities the RAF set up a headquarters in Bangkok, at Don Muang airfield, under Group Captain Don Finlay on September 9, 1945. The headquarters was from No 909 Wing RAF. Three RAF squadrons were represented in Siam during the brief occupation: No. 20 Squadron RAF with Spitfire VIII aircraft, No. 211 Squadron RAF with de Havilland Mosquito VI aircraft, and a detachment of No. 685 Squadron RAF with Mosquito photo-reconnaissance aircraft. The airfield was defended by No. 2945 Squadron, RAF Regiment. Almost all the RAF units had left by January 1946.