1940 Japan forces occupy Vietnam, restricting local French administrators to figurehead authority.
1940 The communists organize the Viet Minh (Viet Nam Doc Lap Dong Minh, or "League for the Independence of Vietnam") to launch an uprising at the war's end.
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1941 Japanese troops occupy Vietnam. The Vichy French colonial government is allowed by the Japanese to continue to administer Vietnam. French repression continues.
1941-1945 The Viet Minh resist Japanese occupation with the help of the United States and China. The Chinese Nationalists set up the Vietnam Revolutionary League (Dong Minh Hoi) as an anti-communist movement. The Chinese Nationalists initially imprison Ho Chi Minh as a communist, but he convinces them he is a Nationalist first and fighting teh Japanese is a comon cause. Ho is set free and given command of the Dong Minh Hoi. Ho returns to Vietnam and rejoins the Viet Minh under Vo Nguyen Giap.
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7 Dec 41 The Empire of Japan attacks the U.S. military forces on Oahu in Hawaii, including the naval base at Pearl Harbor. The USA declares war on Japan, Germany and Italy.
The U.S. Office of Strategic Services (OSS, the forerunner of the CIA) allies with Ho Chi Minh and his Viet Minh guerrillas to harass Japanese troops and to help rescue downed American pilots. Ho Chi Minh becomes "Agent 19" under the supervision of MAJ Archimedes Patti.
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30 Apr 45 US President Franklin D. Roosevelt dies.
30 Apr 45 Major Archimedes Patti US Office of Strategic Services(OSS) meets with Ho Chi Minh who shows his support for America and later asks Patti to take this message back to the American people., ".. . that the Vietnamese loved the Americans; ... tell the Americans that the Vietnamese would never fight the Americans". American arms and instructors support is increased to Ho and Giap.
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8 May 45 Germany surrenders unconditionally to the Allies.
Following the Nazi defeat, the Potsdam Conference is held by the Allies including the U.S., Britain, and Soviet Union to plan the post-war world. Vietnam is considered a minor item on the agenda; in order to disarm the Japanese in Vietnam, the Allies divide the country in half at the 16th parallel. Chinese Nationalists will move in and disarm the Japanese north of the parallel while the British will move in and do the same in the south. During the conference, representatives from France request the return of all French pre-war colonies in Southeast Asia (Indochina). Their request is granted. Vietnam, Laos and Cambodia will once again become French colonies following the removal of the Japanese.
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Aug 45 At a spontaneous non-communist meeting in Hanoi, Ho Chi Minh and the Viet Minh assumed a leading role in the movement to wrest power from the French. With the Japanese still in control of Indochina, Bao Dai went along because he thought that the Viet Minh were working with the OSS and could guarantee independence for Vietnam..
Aug 45 Vietnam's puppet emperor, Bao Dai, abdicates.
Aug 45 Ho Chi Minh's guerrillas occupy Hanoi and proclaim a provisional government in the North of Vietnam.
2 Sep 45 On the deck of the U.S.S. Missouri in Tokyo Bay, Japanese representatives sign the Instrument of Surrender proclaiming their unconditional surrender.
2 Sep 45 Chinese Nationalists accept surrender of Japanese Occupation Forces north of the 16th parallel.
2 Sep 45 The British are to accept surrender south of the line under British Major General Douglas Gracey's 20th Indian Division, some 26,000 men in all. British General Gracey arrives in Siagon (South Vietnam) which is in turmoil.
2 Sep 45 The Communist dominated Viet Minh Independence League with support from United States officials seizes power: Ho Chi Minh establishes the Government of the Democratic Republic of Vietnam (GRDV) in Hanoi, and issues his Declaration of Independence, drawing heavily upon the American Declaration of Independence as well as Sun Yatsen's "Three-people Doctrine".
2 Sep 45 Emperor Bao Dai abdicates
2 Sep 45 Ho Chi Minh writes several letters to US President Harry Truman requesting recognition, citing the Atlantic Charter and then the United Nations Charter on self-determination. He received no response.
Sep 45 The head of the OSS mission in Saigon, COL Peter Dewey, is shot by the Viet Minh, becoming the first American to die in the Viet Nam war.
22 Sep 45 The British release 1,400 French Paratroop POWs from Japanese camps around Saigon. With some of the 20,000 French citizens living there, the French riot, killing Viet Minh suspects and ordinary Vietnamese civilians in Saigon. The defeated Japanese forces are re-armed to assist and restore order. The Viet Minh respond by calling a national strike and organize a guerrilla campaign against the French.
23 Sep 45 French troops return to Vietnam and clash with Communist and Nationalist forces and seize power in the south, with British help.
24 Sep 45 General Jacque Philippe Leclerc arrives in Siagon and declares, " We have come to claim our inheritance". The first Indo-China War of 1946 - 1954, had begun.
Oct 1945 October A purely bilateral British/French agreement recognizes French administration of the southern zone.
Oct 45 In the North 180,000 Chinese troops go on a "rampage". Ho's Viet Minh are hopelessly ill-equipped to deal with it. Ho Chi Minh accepts an Allied compromise for temporary return of 15,000 French troops to rid the North of anti-Communists. The Chinese troops of Chiang flee to Taiwan, looting as they depart.
1945 As World War II ends, starvation kills over 1 million Vietnamese.
http://www.ichiban1.org/html/history/bc_1964_prewar/first_indochina_war_1945_1954.htm There is a very good timeline that continues at the link. As you can see, Ho Chi Minh was mixed up with Allen Dulles. Most people don't realize how much we were entangled in Vietnam before "the war." After WWII, Ho Chi Minh wanted freedom from the French, and he considered due because they fought on the side of the Allies.
However, the US sided with France and ignored Ho. Thus the French got entangled badly after WWII, and we considerately took their place. Ho Chi Minh was a communist and therefore suspect no matter what he had done during the war.
We should have avoided the whole bloody mess. There so many groups with so many agendas involved that who knows what was really going on. In addition, Allen Dulles and his brother John Foster Dulles had probably maintained links there and who knows what they were up to. I'm sure it was no good.
I think the US was manipulated a lot into bad decisions. The government never really did know who all the players were. Shadows everywhere.