The 1945–1946 War in Southern Vietnam, codenamed Operation MasterdomGeorge Rosie and Bradley Borum, Operation Masterdom: Britain's Secret War in Vietnam by the British, and also known as the Southern Resistance War ()Activities mark 75th anniversary of Southern Resistance WarVietnamese Struggle With Their Past: History of the Southern Resistance by the Vietnamese, was an armed conflict in Vietnam south of the 16th parallel during which British-Indian and French forces fought to suppress Vietnamese independence movements, which included nationalists, Trotskyists, and the Stalinist-front Viet Minh, to take control of the southern half of the country. It began shortly after the end of World War II, specifically the unconditional surrender of Japan.

Starting in Saigon on 23 September, the British began facilitating the return of the French to the half of Indochina south of the 16th parallel. Almost all Vietnamese opposed the French return in August 1945, but the Viet Minh's killings of non-communist opponents eventually pushed some groups to join the French in fighting against the Viet Minh. By March 1946, British–French forces had defeated the Vietnamese resistance, allowing the French to reassert control over southern Vietnam. Later, failed negotiations and rising tensions in the north escalated into the full-scale First Indochina War.

Background

In July 1945 at Potsdam, Germany, the Allied leaders made the decision to divide Indochina in half—at the 16th parallel—to allow Chiang Kai-shek to receive the Japanese surrender in the North, while Lord Louis Mountbatten would receive the surrender in the South. The Allies agreed that France was the rightful owner of French Indochina, but because France was critically weakened as a result of the German occupation, a British-Indian force was installed in order to help the French Provisional Government in re-establishing control over their former colonial possession.Joseph Buttinger, Vietnam: A Dragon Embattled (New York: Praeger, 1967, ), p. 244.

After Japan surrendered when Emperor Hirohito announced the capitulation on 15 August, Mountbatten, Supreme Allied Commander of the Southeast Asia Command, was to form an Allied Commission to go to Saigon and a military force consisting of an infantry division that was to be designated as the Allied Land Forces French Indochina (ALFFIC). It was tasked to ensure civil order in the area surrounding Saigon, to enforce the Japanese surrender, and to render humanitarian assistance to Allied prisoners of war and internees.

The concern of the Allies' Far Eastern Commission was primarily with winding down the Supreme Headquarters of the Imperial Japanese Army Southeast Asia and rendering humanitarian assistance to prisoners of war. Major-General Douglas Gracey was appointed to head the Commission and the 80th Brigade, commanded by Brigadier D. E. Taunton, of his 20th Indian Division was the ALFFIC which followed him to Vietnam.

In late August 1945, British occupying forces were ready to depart for various Southeast Asian destinations, and some were already on their way, when General Douglas MacArthur caused an uproar at the Southeast Asia Command by forbidding reoccupation until he had personally received the Japanese surrender in Tokyo, which was actually set for 28 August, but a typhoon caused the ceremony to be postponed until 2 September.

There was also chaos in Indochina—the Japanese had conducted a coup d'état against the French in March 1945 and successfully dismantled their control of Indochina. The Japanese then installed the new Empire of Vietnam under Bao Dai hoping to forestall a potential invasion by the Allies.

MacArthur's order had enormous consequences because the delay in the arrival of Allied troops enabled revolutionary groups to fill the power vacuums that had existed in Southeast Asia since the announcement of the Japanese capitulation on 15 August. In Indochina Japanese garrisons officially handed control to Bảo Đại in the North and the United Party in the South. This, however, allowed nationalist groups to take over public buildings in most of the major cities. The Communists, who exercised complete control over the Viet Minh coalition, founded by Ho Chi Minh in 1941, were thus presented with a power vacuum. The August Revolution commenced forcing Bảo Đại to abdicate in favor of Viet Minh. In Hanoi and Saigon, they rushed to seize the seats of government, by killing or intimidating their rivals.Marvin E. Gettleman, ed., Vietnam and America: A Documented History (Greenwich, Connecticut: Fawcett, 1985), pp. 65–66. The Japanese did not oppose their takeover as they were reluctant to let the French retake control of their colony.Cecil B. Currey, Vo Nguyên Giap – Viêt-nam, 1940–1975 : La Victoire à tout prix, Phébus, 2003, pp. 160–161 Ho Chi Minh proclaimed Vietnam's independence on 2 September 1945.

The Allies, including the United States, stated that the French had sovereignty over Indochina, with America in favor of the return of Indochina to the French;Note: under the terms of the 1941 Atlantic Charter signed by both Churchill and Roosevelt, the successful ending of the war with the Allies victorious required the previous legitimate pre-war governments of occupied territories to be re-instated, thus restoring the pre-war status quo, the principle being that no-one should benefit from the acts of aggression by the Axis powers. but there was no official American animosity towards the Communist-led Viet Minh.Lloyd Gardner, Approaching Vietnam (New York. Korton, 1988), p. 25.The first Vietnam War, by Mark Atwood Lawrence, Fredrik Logevall

MacArthur received the Japanese surrender on board the battleship on 2 September, and three days later the first Allied medical rescue teams parachuted into the prisoner of war camps. During the following days a small advance party of support personnel and infantry escort from Gracey's force arrived in Saigon to check on conditions and report back; on the 11th a brigade was flown in from Hmawbi Field, Burma via Bangkok. When these advance Allied units landed in Saigon they found themselves in a bizarre position of being welcomed and guarded by fully armed Japanese and Viet Minh soldiers. The reason these soldiers were armed was because six months earlier (9 March) they disarmed and interned the French, for the Japanese feared an American landing in Indochina after the fall of Manila and did not trust the French.

Many political activists in the former French Cochinchina, of very different political beliefs, were highly educated and influenced by Western thought, and often interacted with each another. However, the Stalinist Viet Minh leadership in Hanoi resolved to assassinate or execute all Trotskyist and nationalist figures who opposed their centralized authority. Among those targeted were Bùi Quang Chiêu, Hồ Văn Ngà, Dương Văn Giáo, Tạ Thu Thâu, Trần Văn Thạch, Phan Văn Chánh, Phan Văn Hùm, Huỳnh Văn Phương, Lâm Ngọc Đường, Hồ Vĩnh Ký, Nguyễn Thị Sương, Lê Văn Vững, and Nguyễn Văn Sâm.

British involvement

Upon Gracey's arrival on 13 September to receive the surrender of Japanese forces, he immediately realized the seriousness of the situation in the country. Saigon's administrative services had collapsed, and a loosely controlled Viet Minh-led group had seized power. In addition, since the Japanese were still fully armed, the Allies feared that they would be capable of undermining the Allied position. Furthermore, Gracey had poor communications with his higher headquarters in Burma because his American signal detachment was abruptly withdrawn by the U.S. government for political reasons; it was a loss that could not be rectified for several weeks.

Gracey wrote that unless something were done quickly, the state of anarchy would worsen. This situation was worsened by the Viet Minh's lack of strong control over some of their allied groups. Because of this, the French were able to persuade Gracey (in a move which exceeded the authority of his orders from Mountbatten) to rearm local colonial infantry regiments who were being held as prisoners of war.

Gracey allowed about 1,000 former French prisoners of war to be rearmed. They, with the arrival of the newly formed 5th Colonial Infantry Regiment (RIC) commandos, would then be capable of evicting the Viet Minh from what hold they had on the Saigon administration. Gracey saw this as the quickest way to allow the French to reassert their authority in Indochina while allowing him to proceed in disarming and repatriating the Japanese.

Gracey faced another problem in his relations with Mountbatten. One example of this occurred on Gracey's arrival in September. He drew up a proclamation that declared martial law and stated that he was responsible for law and order throughout Indochina south of the 16th parallel. Mountbatten, in turn, made an issue of this, claiming that Gracey was responsible for public security in key areas only. The proclamation was published on 21 September and, although Mountbatten disagreed with its wording, the Chiefs of Staff and the Foreign Office supported Gracey.

During the following days, Gracey gradually eased the Viet Minh grip on Saigon, replacing their guards in vital points with his own troops which were then turned over to French troops. This procedure was adopted because the Viet Minh would not have relinquished their positions directly to the French.Philip Ziegler, Mountbatten (New York: Knopf, 1985), p. 331.

Allies reassert control in Saigon By 23 September, most of Saigon was back in French hands, with less than half a dozen vital positions in Viet Minh control. The French subsequently regained total control of Saigon. On that day, former French prisoners of war who had been reinstated into the army together with troops from the 5th RIC ejected the Viet Minh in a coup in which two French soldiers were killed.

That same day, the local French population, jubilant at the restoration of the city, lost restraint, descending into rioting against the native population. This led to the events of 24-25 September, when a Vietnamese mob (alleged to be the Bình Xuyên, but later found to be Trotskyists), entered the Cité Hérault district of Saigon, lynching 150 French civilians while abducting a similar number - who later also perished. At the same time, the Viet Minh set up road blocks around Saigon, shooting Frenchmen who attempted to leave and accidentally killing OSS agent A. Peter Dewey, the first American to die in Vietnam. Elsewhere on the 25th, the Viet Minh attacked and set fire to the city's central market area, while another group attacked Tan Son Nhut Airfield. The airfield attack was repelled by the Gurkhas, where one British soldier was killed along with half a dozen Viet Minh. The British now had a war on their hands, something which Mountbatten had sought to avoid.

For the next few days, parties of armed Viet Minh clashed with British patrols, the Viet Minh suffering mounting losses with each encounter.George Rosie, The British in Vietnam (London: Panther Books, 1970). The British soldiers were experienced troops who had just recently finished battling the Japanese; many officers and soldiers had also experienced internal security and guerrilla warfare in India and the North West Frontier. In contrast the Viet Minh were still learning how to fight a war.