Indecisive[1] Vichy France Thailand 1941 1942 1943 1944 1945 1941 1942 1944 1945 Second Sino-Japanese War Taishō period Shōwa period Asia-Pacific Mediterranean and Middle East Other campaigns Coups Second Third The Franco-Thai War (October 1940 – 28 January 1941, Thai: กรณีพิพาทอินโดจีน, romanized: Karani Phiphat Indochin; French: Guerre franco-thaïlandaise) was fought between Thailand and Vichy France over certain areas of French Indochina.

The French's seemingly subservient behavior lulled the Phibun regime into believing that France would not seriously resist a military confrontation by Thailand.

The Vichy French Air Force (Armée de l'Air) had approximately 100 aircraft, of which roughly 60 could be considered front-line.

The Royal Thai Navy included two Thonburi-class coastal defense ships, 12 torpedo boats, and four Japanese-made submarines.

[5] While nationalist demonstrations and anti-French rallies were being held in Bangkok, several border skirmishes erupted along the Mekong frontier.

The superior Royal Thai Air Force then conducted daytime bombing runs over military targets in Vientiane, Phnom Penh, Sisophon, and Battambang with impunity.

The Thai army swiftly overran Laos, but the French forces in Cambodia managed to rally and offer more resistance.

[15] At dawn on 16 January, the French launched a large counterattack on the Thai-held villages of Yang Dang Khum and Phum Preav, initiating the fiercest battle of the war.

On 24 January, the final air battle took place when Thai bombers raided the French airfield at Angkor, near Siem Reap.

A general ceasefire had been arranged to go into effect at 10:00 on 28 January, and a Japanese-sponsored "Conference for the Cessation of Hostilities" was held at Saigon, with preliminary documents for an armistice between the governments of Marshal Philippe Pétain's French State and the Kingdom of Thailand signed aboard the cruiser Natori on 31 January 1941.

On 9 May, a peace treaty was signed in Tokyo,[12][13] with the French being coerced by the Japanese to relinquish their hold on the disputed border territories.

[16] Relations between Japan and Thailand were subsequently stressed, as a disappointed Phibun switched to courting the British and Americans to ward off what he saw as an imminent Japanese invasion.

[18] This led to the conclusion of the Franco-Siamese Settlement Treaty of 1946 that settled the issue and paved the way to restoration of diplomatic relations between the two countries.

About 30 percent of the French aircraft were rendered unserviceable by the end of the war, some as a result of minor damage sustained in air raids that remained unrepaired.