Battle of Koh Chang

The Battle of Koh Chang took place on January 17, 1941 during the French-Thai War and resulted in a decisive victory by the French over the Thai Navy. Despite the fall of France in 1940 the Vichy government still held sway over France's colonial territories abroad. One of these territories was French Indochina, what we know today as Vietnam. With the defeat of mainland France obvious doubt was thrown over her ability to defend the far flung outposts of the empire. French Indochina held a particular attraction to her neighbor to the West, Thailand.

During the war years, one of the aims of the Siam (Thai) military government of that time was to promote patriotism among Thai people. The sentiment of the day was to reclaim the former Siam’s lands in Indochina (Laos, Cambodia and Vietnam). These lands once belonged to Siam, before they were being aggressively pursued by a series of forced annexations by French Colonialism in years between 1867-1906, under the reign of King Chulalongkorn. The defeat of France by the Nazi military stimulated Thai military government to start the plan of getting back the lost territories.

In late 1940 the Thais began a series of raids by troops and aircraft against the French possessions, aimed at annexing those parts of French Indochina which the French were unable to hold on to. These attacks tended to concentrate in the coastal regions of Cambodia, to the west of Saigon. The Thais naturally saw themselves as filling a power vacuum which had been created by deflating French colonial interests. The French, however, had other ideas and a state of war was assumed between Vichy France and Thailand (then still often referred to as Siam). Since the main thrust of the Thai assaults had been along the coast the French considered a naval operation against the invaders, although there was grave concern over strengths of the Thai armed forces which would oppose such a mission.

Thai Navy
The Royal Thai Navy could in no way be regarded as a pushover. A number of new vessels had recently been delivered from Japan and Italy. The major units of the fleet included two Japanese-built armored coast defense vessels which displaced 2,500 tons and carried 8" guns, two older British built armored gunboats with 6 inch guns, twelve torpedo boats and four submarines. In addition the Royal Thai Air Force had in its inventory over 140 aircraft, including relatively modem Mitsubishi Ki-30 light bombers, which saw extensive service against the French. These aircraft in themselves were quite capable of causing severe damage to any French naval mission which may be mounted. Other less capable aircraft in the Thai inventory included P-36 Hawk fighters, 70 Chance-Vought O2U-2 Corsair biplanes, 6 Martin B-10 bombers and several Avro 504 trainers.

Initial French moves
Despite the strengths of the Thai forces the French Governor General of Indochina and Commander-in-Chief Naval Forces, Admiral Jean Decoux, decided that the naval mission should go ahead. A small squadron, the Groupe Occasionnel, was formed on 9th December 1940 at Cam Ranh Bay, near Saigon, under the command of Capitaine de Vaisseau Régis Bérenger. The squadron consisted of the light cruiser Lamotte-Piquet, the colonial sloops Dumont d'Urville and Amiral Charner, and the older sloops Tahure and Marne. There was no air cover to speak of, apart from eight Loire 130 seaplanes based at Ream which provided reconnaissance. Additional scouting was provided by three coastal survey craft, and intelligence gleaned from the local fishermen.

Bérenger's squadron began training maneuvers in Cam Ranh Bay shortly after coming together. Early in the New Year, on January 13, 1941, Admiral Decoux formally requested Bérenger to send the squadron against the Thais to act in support of a land offensive planned for January 16. This operation was intended to throw back Thai forces which had been advancing along