The city of Bangkok, Thailand was bombed by the Allies on numerous occasions during World War II because of its strategic importance as the logistic and command center for the Japanese Southeast Asian operations in their Burma and Malayan campaigns. Thailand would eventually declare war against the Allies on January 1942 making Bangkok a prime target for the Allied air forces.
The British and American bombings were aided by the Free Thai Movement, an Allied-aligned, anti-Japanese guerilla movement running by both Thai civilians and officials. Agents of the Free Thai Movement designated targets and locations of strategic Japanese positions and even reported on the weather over the targets for Allied aircraft.
Bangkok was also selected as the target for the first combat mission by Boeing B-29 Superfortresses in June 1944.
Initial Allied air raids
Allied bombing raids on the Thai capital city of Bangkok began even before Thailand had declared war against the Allied Powers, since the Empire of Japan was using the country as a staging area for its invasions of both Malaya and Burma, with the reluctant agreement of the Thai government after Japan's successful invasion of the southeast Asian country on 8 December 1941. The Thai-Japanese declaration of Alliance was signed on 21 December 1941, with proper declaration of war against the United States and Great Britain occurring on 25 January 1942.
The first raid on Bangkok came on the night of 7-8 January 1942 at 02.00 AM, when Royal Air Force (RAF) aircraft flying from Rangoon, attacked military targets in the city such as Hua Lamphong railway station and Memorial Bridge. The American Volunteer Group, together with seven No. 113 Squadron RAF and three No. 45 Squadron RAF Bristol Blenheim bombers, were involved in the first raid. No. 113 Squadron's planes were piloted by No. 60 Squadron's air crew. Thai damage reports stated that Yaowarat Chinatown was erupted in flames, and other bomb hits were reported at Charoen-Sawat Bridge, Ministry of Interior building at Phra Nakhon district, Bang Rak Hospital and the famous "7-Story Building" of Yaowarat. 112 wounded and 31 deaths are reported as casualties, mostly Chinese and Muslims.
The second night raid was carried out by eight Bristol Blenheims on 24–25 January at 20.30 PM and included aircrew from No. 60 Squadron RAF. Some bombers were diverted towards the Ananta Samakhom Throne Hall then used as Thai Parliament to bomb nearby military installations. Thai anti-aircraft units, equipped with Type 77 Bofors anti-aircraft guns with the aid of Type 77 spotlight, fought fiercely against British bombers until 23.00 PM when all bombers returned to their base. Three Thai guards are killed, and 10 bombs hit the area of Throne Hall with four bombs proved to be duds and another two hit Throne Hall itself. One of the aircraft participating in the raid was shot down and crashed at Talat Phlu, then part of Thonburi Province across the Chao Phraya River with all crew lost. Thai writers Khun Wichitmatra and Ajin Panjapan witnessed this air crash.
The final RAF Blenheim raid against Thai targets in Bangkok and Thonburi was made three days later on 28 January by four Blenheims at 20.30 PM. The objective was Wat Liap Powerplant but the bombs missed and hit Chucheep Market and Kasat Suek Bridge instead while Wat Liap Powerplant received no damage. Thai navy shot-down one of the bombers at Thonburi with all crews lost.
During the period of January 1942, six aerial missions had been conducted against Bangkok – this divided into 3 bombing missions and 3 photo recon missions.
Allied heavy-bomber air raids against Bangkok
After the January 1942 raids by the Royal Air Force, the Thai government ordered a massive construction plan for air raid shelters to be built within Bangkok. Some air raid shelters were large governmental structures that could accommodate many individuals. One such large building used to be accessible is at Dusit Zoo (before it was permanently closed to the public when the Dusit area itself was returned to the crown land status in 2018). Some were mere covered ditches that were often flooded with rainwater. But at this stage of the war, British twin-engined bombers went completely silent because the Japanese had completely taken hold of most British colonies in Southeast Asia from Burma to Malaya. With normal daytime life starting to resume in Bangkok, the lights-out period at night were still enforced by the state.
After Rangoon fell to the Japanese on 7 March, heavy bombers, such as the RAF and American Tenth Air Force Consolidated B-24 Liberators, based in India and China, attacked targets in Thailand. The raids were carried out because Bangkok by then had become a command center for the Japanese on the Southeast Asian front. RAF and United States Army Air Forces (USAAF) bombers carried out the raids as part of the Pacific campaigns. The bombers struck installations used by the occupying Japanese military, but the raids were also intended to pressure the government of Thai military strongman Plaek Pibulsongkram to abandon his unpopular 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 3 May 1945, from Rangoon until the end of the war in August of that year.
1942 was characterized by a massive monsoon season which jeopardized the situation of the campaign in Burma. A June report from the Argus Newspaper stated both Allied and Japanese troops were forced to use heavy machinery, elephants and barges to supply their troops during the consecutive rainfall. In Thailand, the historic flood of the century arrived in its infancy in July 1942, when massive rainfall in the northern parts of Thailand ended up flooding Ping River, Wang River and Nan River – all are considered as major tributaries that led to Chao Phraya River and Bangkok. In late-September the flood reached Bangkok, and the people of Bangkok resorted to using their personal boats as their roads and tram lines became impassable.
American Bomber Missions 1942-1945
On 3 December 1942, CBI Roundup reported that India Air Task Force (Part of the Tenth Air Force, organized on 8 October 1942 with Brigadier General Caleb V. Haynes as a unit commander) attacked Japanese refinery in Bangkok Thailand. The attacks also included two night raids on Rangoon and a raid on Port-Blair in Andaman Sea. Several days later on 26 December 1942, US Tenth Air Force bombers from bases in India attacked Hua Lamphong railway station and the port of Khlong Toei, Bang Sue Arsenal, Samsen and Wat Liap Power Plants. After this December attacks, the bombing raid against Bangkok would be stopped for the next eight months until April 1943.
1943, B-24 Liberators of the Tenth Air Force resume their attacks on Bangkok. On 13 April 1943, 16 B-24 Liberators are launched against the Bang Sue Arsenal but only 4 reached its destination. Later on, 19 and 23 December 1943 American Liberators are sent to raid Hua Lamphong station and Khlong Toei ports respectively. It was also reported that on the night of 23 December, US Bombers have dropped illumination flares to guide their nighttime bombing. These are the only US raids against Bangkok in 1943.
In Tenth Air Force's perspective, 1944 is the year with most Bangkok bombing missions. Starting with January 10 air raid, the raid was divided into two objectives. First is minelaying mission at the estuary of the Chao Phraya River (Pak Nam) to block the Japanese-Thai shipping in the area. Another mission of the January 10 raid is the Marshalling Yard at Bang Sue and the Don Muang Airbase jointly operated by Thai and Japanese forces. The Tenth Air Force would continue to launch more raids against various targets around Bangkok for the rest of the year. (Two Missions in January, two in February, one in March, one in June, one in November and December) Tenth Air Force was joined by Fourteenth Air Force (Kunming) and Twentieth Air Force (Calcutta) with one January mission from the Fourteenth Air Force and six missions from the B-29 of the Twentieth Air Force from June towards the end of the year. For the Americans the B-24's role of bombing of Bangkok in 1945 is completely replaced by the newer B-29 from the Twentieth Air Force in Calcutta resulting in two January missions and one February mission.
British Bomber Missions
On the other hand, British Commonwealth also conducted their own air operations against Bangkok.
An account of Wing Commander J. Blackburn of No. 159 Squadron RAF in July-December points out that Japanese aerial resistance have become so rare he ordered his men to remove armor platings and reduce machine gun ammunition from their Liberators to reduce their weight. The payload has been increased to 8000 lbs for Bangkok and 12000 lbs for Rangoon. Some Liberators from No. 159 Squadron are also tasked with signal-intelligence role along the Bangkok-Moulmein rail line.
Liberators from No. 356 Squadron RAF attacked Wat Liap Powerplant on 16 April 1945 followed by the attack at the Khlong Phasi Charoen canal locks near Bangkok on 18 April 1945 by 8 Liberators all carried seven 1000 lbs bombs with one Liberator (B-24J/Liberator Mk.VI) nicknamed "Daedalus", serial KH272 crashed at Bang Yang canal locks gate (ประตูระบายน้ำบางยาง) after an explosion occurred within its bomb bay.
Thai and Japanese responses to Allied bombing raids
Japanese Prime Minister Hideki Tojo visited Bangkok on 3-6 July 1943 as a part of his Asian Tour. He visited Bangkok to discuss about the handover of Malay and Shan states to Thai control with Marshal Phibun. On 3 July 1943, Tojo and Phibun went to pay their respect to the Temple of the Emerald Buddha or Wat Phra Kaew. Tojo reportedly said to Lieutenant General Aketo Nakamura, Japanese commander of the Thailand Garrison that Wat Phra Kaew must be defended by anti-aircraft guns. Nakamura then explains to Tojo that the Japanese have only one anti-aircraft unit in Bangkok, combined with few Thai anti-aircraft units it is unable to defend Bangkok from further air attacks.
The Royal Thai Air Force have organized an air wing to protect its capital in the form of 15th Fighter Squadron (also known as Capital Defense Fighter Squadron, ฝูงบินขับไล่รักษาพระนคร or 15th Hiko Chutai in Japanese) at Don Mueang air force base. The squadron operated 24 Nakajima Ki-43 Hayabusa fighters transferred from Japanese bases in Syonan (Singapore) with Thai "Running Elephant" roundels painted on its wings and tail section to differentiate themselves from Allied roundels.
Thai pilots are trained at Japanese-occupied Singapore and flew the planes back to Don Mueang by themselves. The Royal Thai Air Force sent three pilots to Singapore to train with Hayabusa, Squadron Leader Sakol Rasanont (นาวาอากาศตรี สกล รสานนท์), Flight Lieutenant Harinth Hongsakul (เรืออากาศเอก หริญ หงส์สกุล) and Flight Lieutenant Dawee Chullasapya (เรืออากาศเอก ทวี จุลทรัพย์) all pilots are trained with Japanese instructor named Nakamura from 3rd Chutai of the 64th Sentai. Story of Thai pilots and Hayabusa fighters have been a subject of some films, firstly a surviving Japanese newsreel (Released by NHK after the war) showed how Thai ground crews are trained with their newly received fighters at Don Mueang airbase while repainting Thai insignia onto each planes. Another Thai-produced film dubbed "The Night Pilot" (นักบินกลางคืน) have been destroyed from Post-War political reasons.
On 18 November 1944, 10 B-24 attacked Bang Sue rail junction. The Royal Thai Air Force deployed three Ki-43 Hayabusa piloted by Flight Lieutenant Therdsak Worrasap (เรืออากาศเอก เทอดศักดิ์ วรทรัพย์) veteran of the Franco-Thai War with one Morane-Saulnier MS.406 kill during that conflict, Pilot Officer Mom Rajawongse Priyasuwan Chakkrapant (เรืออากาศตรีหม่อมราชวงศ์ ปรียะสุวรรณ จักรพันธ์) and Flight Sergeant First Class Wichean Booranarech (พันจ่าอากาศเอก วิเชียร บูรณเรช) to intercept Allied bombers. But all bombers have left the vicinity before Thai fighters could reach them.