This would, according to imperial propaganda, establish a new international order seeking "co-prosperity" for Asian countries which would share prosperity and peace, free from Western colonialism and domination under the umbrella of a benevolent Japan.

[8] Thailand had a well-disciplined military, and after a series of border skirmishes in 1940 had invaded neighbouring French Indochina to recover provinces lost in the Franco-Siamese crisis of 1893.

[9] As part of the process, secret discussions were held with Thai Prime Minister Plaek Phibunsongkhram, in which the Japanese military sought free passage through Thailand.

By February, the British were beginning to suspect the Japanese were planning to attack their possessions in Southeast Asia and were concerned Japan might set up bases in Thailand to that end.

The Japanese sought to have the sanctions lifted by promising not to encroach on Thailand and withdrawing their forces from Indochina, provided the United States withdrew its support for China.

In late November, the British became aware of a probable attack on Thailand by Japan because of the rapid buildup of Japanese troops in Indochina.

[12] On 1 December 1941, Prime Minister Hideki Tojo of Japan stated that he was uncertain where Thailand stood regarding allowing Japanese troops free passage through its territory, but was hopeful a clash could be avoided.

[14] On 2 December, the Japanese military issued the order "Climb Mount Niitaka", which set in motion the war in the Pacific.

The preservation of the true independence and sovereignty of Thailand is a British interest, and we shall regard an attack on you as an attack upon ourselves.At noon on 6 December, one of three RAAF No 1 Squadron Lockheed Hudsons on a reconnaissance flight over the South China Sea, located three Japanese ships steaming west, and about 15 minutes later, sighted the IJN Southern Expeditionary Fleet convoy, consisting of a battleship, five cruisers, seven destroyers and 22 transports.

One of the two merchant seaplane tenders with the convoy, the Kamikawa Maru, launched a Mitsubishi F1M "Pete" floatplane to intercept the Hudson, which eluded it by taking cover in the clouds.

About 20 nmi (37 km) west northwest of Panjang Island at 08:20, an E13A1 ZI-26 from the Kamikawa Maru, piloted by Ensign Ogata Eiichi, spotted a No.

205 Squadron RAF Consolidated PBY Catalina reconnaissance flying boat (W8417), piloted by Warrant Officer William E Webb.

The Royal Thai Navy was poorly trained and equipped, and had lost a substantial number of vessels in its conflict with French Indochina.

Ships from IJN 2nd Fleet under Admiral Nobutake Kondō provided support and cover for the landings in Thailand and at Kota Baru in Malaya.

[25] At dawn the Imperial Guards Division under Lieutenant-General Takuma Nishimura and IJA 55th Division under Lieutenant-General Hiroshi Takeuchi of the 15th Army crossed the border from Indo-China into Thailand's recently reclaimed Phra Tabong Province at Tambon Savay Donkeo, Athuek Thewadej District (Russei) of Battambang.

The Thai had lost Captain Thawin Niyomsen (commanding the 52nd Yuwachon Thahan Unit, posthumously promoted to Lt. Col.), some provincial policemen and a few civilians.

Three Japanese troopships, Zenyo, Miike, and Toho Maru, landed troops at Nakhon Si Thammarat, covered by the Shimushu, dropped anchor a few kilometres off the coast during the night of 7 December.

The Japanese laid siege to the airfield, but the Thai airmen along with Prachuap Khirikhan Provincial Police managed to hold out until noon on the next day, when they too received the ceasefire order.

Despite a tense confrontation, fighting did not occur and the Japanese subsequently agreed not to enter the Thai capital until formal negotiations were concluded.

While police rounded up Japanese residents, the Thai cabinet debated its options while they waited for the prime minister to arrive.

[32] Some favoured continued resistance, including the establishment of a government-in-exile, but when Phibun finally arrived, the decision was made to relent, and the Thais caved into Japan's demands.

The Japanese then moved into Bangkok, occupying Chinatown (Sampeng) and turning the Chamber of Commerce Building into a command post.

The desultory fighting took place amid a rainstorm, and only ended in the afternoon when the hard-pressed Thais received orders to lay down their arms.

The Thai battalion commander, Khun (ขุน) Inkhayutboriharn, was killed in action along with 23 other ranks, 5 Provincial Police, 4 Yuwachon Thahan members, and 9 civilians.

[36] Major Shigeharu Asaeda, when a member of Taiwan Army Unit 82, had been involved with intelligence-gathering in Burma, Thailand, and Malaya prior to the outbreak of war and had selected Pattani as a suitable landing site.

During the early hours of 8 December, three regiments of the Japanese 5th Division led by Colonel Tsuji under Lieutenant General Matsui Takuro landed there from 10 troop transports.

[citation needed] Phibun's decision to sign an armistice with Japan effectively ended Churchill's hopes of forging an alliance with Thailand.

Within hours after the armistice came into effect, squadrons of Japanese aircraft had flown into Songkla airfield from Indochina, allowing them to carry out air raids on strategic bases in Malaya and Singapore from a short distance.