The first instance of France-Thailand contacts is also the first historical record of an attempt to introduce Christianity to Siam: according to Giovanni Pietro Maffei, about 1550 a French Franciscan, Bonferre, hearing of the great kingdom of the Bagoans and the Thai in the east, went on a Portuguese ship from Goa to Cosme (Bago), where for three years he preached the gospel without any result.

[1] The first major contacts between the two countries occurred after Thailand was made an apostolic vicariate by Pope Alexander VII on 22 August 1662.

[4] Bishops Lambert and Ballue established a Western hospital in Thailand in 1669 at Ayutthaya, with Father Laneau as the head doctor.

[8] In September 1680, a ship from the French East India Company visited Phuket and left with a full cargo of tin.

Artists in Paris produced scores of prints depicting the Siamese diplomats and the lavish receptions at Versailles and Ayutthaya.

[10] King Narai further sought to expand relations with the French, to counter Portuguese and Dutch influence in his kingdom, and at the suggestion of his Greek counselor Constantine Phaulkon.

In 1680, a first Siamese ambassador to France was sent in the person of Phya Pipatkosa on board the Soleil d'Orient, but the ship was wrecked off the coast of Africa after leaving Mauritius and he disappeared.

His position, however, was soon made untenable by the jealousy and intrigues of the minister Constantine Phaulkon, and after two years he left Siam, reaching France in 1688.

He began by building a fortress in Bangkok,[8] and designed fortifications for Ligor (Nakhon Sithammarat), Singor (Songkhla), Phatthalung, Ayutthaya, Louvo (Lopburi), Mergui, Inburi and Thale Chupson.

Kosa Pan was accompanied by two other Siamese ambassadors, Ok-luang Kanlaya Ratchamaitri and Ok-khun Si Wisan Wacha,[8] and by the Jesuit Father Guy Tachard.

The mission landed at Brest, France and traveled overland to Versailles, constantly surrounded by crowds of curious onlookers.

In place of Samuel White, the French Chevalier de Beauregard was nominated Governor of Mergui by the king of Ayutthaya in 1687.

[8] The military wing was led by General Desfarges, and the diplomatic mission by Simon de la Loubère and Claude Céberet du Boullay, a director of the French East India Company.

[8] Desfarges commanded the fortress at Bangkok, with 200 French officers and men,[8] and a Siamese contingent provided by King Narai.

[24] Meanwhile, the Jesuit Guy Tachard returned to France with the title of "Ambassador Extraordinary for the King of Siam", accompanied by Ok-khun Chamnan, and visited the Vatican in January 1688.

[8] Two weeks later a military treaty was signed, designating François d'Alesso, Marquis d'Eragny, as captain of the palace guard in Ayutthaya and inspector of the French troops in Siam.

[8] The landing of French troops in Bangkok and Mergui led to strong nationalistic movements in Siam directed by the Mandarin and Commander of the Elephant Corps, Phra Petratcha.

[8] Desfarges finally negotiated to return with his men to Pondicherry on 13 November, on board the Oriflamme and two Siamese ships, the Siam and the Louvo, provided by Phetracha.

[8] On 10 April 1689, Desfarges, who had remained in Pondicherry, led an expedition to capture the island of Phuket in an attempt to restore some sort of French control in Siam.

[8] Desfarges died on board near Martinique, and the Oriflamme sank on 27 February 1691, with most of the remaining French troops, off the coast of Brittany.

He met with Kosa Pan, now Minister of Foreign Affairs and Trade, and the new King Phetracha, but the meeting remained purely formal and led to nothing.

A treaty was signed on 15 August 1856, to facilitate trade, guarantee religious freedom, and grant French warships access to Bangkok.

In June 1861, French warships brought a Thai embassy to France, led by Phya Sripipat (Pae Bunnag).

Under the orders of Napoleon III, French gunships under Charles Rigault de Genouilly attacked the port of Da Nang in 1858, causing significant damage, and holding the city for a few months.

In 1893, the French authorities in Indochina used border disputes, such as the Grosgurin affair and the Paknam naval incident, to provoke a crisis.

In exchange, Siam gave up its claim to the Tai-speaking Shan region of north-eastern Burma to the British, and ceded Laos to France.

This time Siam had to concede French control of territory on the west bank of the Mekong opposite Luang Prabang and around Champasak in southern Laos, as well as western Cambodia.

Trat became part of Thailand again on 23 March 1907 in exchange for areas east of the Mekong river including Battambang, Siam Nakhon, and Sisophon.

In the early 20th century these crises were adopted by the increasingly nationalist government as symbols of the need for the country to assert itself against the West and its neighbours.

The war ended in May with the help of the Japanese, allied with Nazi Germany, who coerced the French to relinquish their hold on the disputed border territories.