[1][2] The incident, also known as the Shelling of Haiphong, is thought of as the first armed clash in a series of events that would lead to the Battle of Hanoi on December 19, 1946, and with it the official outbreak of the First Indochina War.

[8] Specifically, the Japanese renounced French claims to the Vietnamese territory on March 9, 1945, officially declaring Vietnam independent over France and under the control of Emperor Bảo Đại.

[9] This was counteracted by a rebellion on September 2, 1945, when Ho Chi Minh and his guerilla army declared the official birth of the Democratic Republic of Vietnam.

However, complete colonization was no longer an option due to power dynamics in the west and on March 6, 1946, after receiving pressure from the western allies, Jean Sainteny, French Commissioner for Northern Indochina met with Ho Chi Minh in Hanoi and signed the Ho–Sainteny agreement.

[11] The agreement officially gave Vietnam independence as "a free state with its own government, parliament, army and finances, forming part of the Indochinese Federation and the French Union".

The Vietnamese leadership, led by Ho Chi Minh, settled to sign a modus vivendi, postponing talks to a later date.

[17][22] The French immediately worked to dissipate the conflict and stopped the outbreak by agreeing to respect Vietnamese sovereignty in Haiphong on November 22, 1946.

Valluy, in turn, sent an order to Colonel Debès, commander of the French troops at Haiphong, stating, "It appears clear that we are up against premeditated aggressions carefully staged by the Vietnamese regular army ...

[28] The role of the cruiser Suffren in the bombardment is controversial, as some versions of events suggest the ship participated in the shelling and others claim it arrived after the action had already been carried out.

[31] The historian Georgette Elgey considers this estimate to be perhaps excessive as it represents 10% of the city's population, but nevertheless describes the incident as by far the deadliest of the war.

[35][36] The threat of the French establishing a separate southern state in Vietnam by besieging the city of Hanoi became a top priority for the Viet Minh to counteract.

The Hanoi Committee of the Việt Minh Front calls on the people to be calm, to be united, and to be ready to rise when the government gives the order [to rebel against the French].

"[25] The Vietnamese people, in turn, reacted to the plea to prepare, building barricades in the streets of Hanoi and engaging in armed skirmishes with French legionnaires.

[40] The final ultimatum to the Vietnamese was issued on December 19, when General Morlière ordered the leading Viet Minh militia, Tu Ve ("self-defence"), to completely disarm.

[41] The Vietnamese (specifically the Tu Ve militia) attacked the French from within Hanoi with machine guns, artillery, and mortars.