On November 23, 1946 the French navy bombarded the Vietnamese coastal city of Haiphong, killing 6,000 Vietnamese people overnight. The Haiphong shelling was the first in a series of armed clashes leading to the December Battle of Hanoi and the outbreak of the First Indochina War.
On December 19, 1946, 30,000 Viet Minh initiated their first large-scale attack on the French in the Battle of Hanoi. War had begun again in Viet Nam.
This (undated) pro-French propaganda film seems to capture the events of the times.