In June 1940, France was defeated by Germany and the Vichy government took power. This weakened French authority in Indochina and made it harder to resist pressure from Japan, which was expanding its war in East Asia.
On 22 September 1940, Japan entered northern Indochina (Tonkin) after extracting an agreement from Vichy French authorities for military access, including airfields. Fighting broke out immediately in border areas, showing that Japanese control would be enforced by force as well as diplomacy.
From 22–25 September 1940, Japanese forces attacked French positions around Lạng Sơn near the Chinese border. The battle confirmed Japan’s ability to impose its demands militarily, even while France’s colonial administration remained in place on paper.
In early 1941, Hồ Chí Minh returned to Vietnam and helped rebuild an organized independence movement near the northern border. This mattered because it connected local anti-colonial activism to a coordinated plan for national liberation during wartime disruption.
On 19 May 1941, the Việt Minh (League for the Independence of Vietnam) was formed at Pác Bó. It was designed as a united front—bringing different patriotic groups together—aimed at ending foreign control, including both French colonial rule and the Japanese military presence.
In 1941 Japan expanded from the north into southern Indochina, gaining new military positions closer to British Malaya and the Dutch East Indies. This deepened Vietnam’s status as a wartime logistics hub and increased Japanese demands on the local economy and administration.
From about October 1944, a severe famine spread across northern and north-central Vietnam. Wartime policies and disruptions—including forced requisitions, transport breakdowns, and Allied bombing impacts—combined with poor harvests, leading to mass starvation.
On 9 March 1945, Japan carried out a coup across Indochina, disarming and dismantling the French colonial military and administrative system. This ended the earlier arrangement where French officials governed day-to-day under Japanese oversight, and it created a sudden power vacuum.
On 11 March 1945, Emperor Bảo Đại declared Vietnam’s independence from France under Japanese direction, forming the short-lived Empire of Vietnam. Although presented as independence, Japanese troops remained in control, limiting the new government’s real sovereignty.
By spring 1945 the famine reached catastrophic levels, with estimates ranging from hundreds of thousands to around two million deaths. The scale of suffering weakened confidence in existing authorities and helped create conditions where revolutionary organizers could gain support and control locally.
From 13–28 August 1945, the Việt Minh organized uprisings and took over many administrative centers, including Hanoi on 19 August. Japanese forces largely stood aside as Vietnamese groups moved to fill the vacuum left by the collapse of colonial control.
On 15 August 1945, Japan announced it accepted Allied surrender terms. In Vietnam, this sharply reduced Japan’s ability to govern, and it accelerated a scramble for power between existing imperial institutions, local groups, and the Việt Minh.
On 25 August 1945, Bảo Đại abdicated in response to the revolutionary takeover, signaling the end of the Empire of Vietnam and the Nguyễn monarchy’s political role. This transfer of authority strengthened the Việt Minh claim to represent a new national government after the Japanese occupation.
On 2 September 1945, Hồ Chí Minh publicly declared the Democratic Republic of Vietnam in Hanoi, framing it as independence from France. In the south, British-led forces soon arrived in Saigon to accept the Japanese surrender, showing that the end of Japanese occupation did not mean stability or international recognition.
Japanese occupation of Vietnam (1940–1945)