During the French Indochina War, the Vietminh . avoided major military engagements shelled the city of Haiphong, killing 6,000 civilians relied on hit and run tactics received support from the Bao Dai government, relied on hit and run tactics helped the city of Haiphong, killing 6,000 civilians.

Relied on hit and run tactics, is the right answer.

Explanation:

A war fought between 19th December 1946 to 20th July 1954 in French Indochina came to be known as the First Indochina War. This war in Vietnam was commonly known as the Anti-French Resistance War. This was a conflict in which a range of forces was included, for instance, the French Far East Expeditionary Corps supported by the Vietnamese National Army fighting against the Việt Minh and the People's Army of Vietnam.

In this war, the Việt Minh employed the hit-and-run tactic against the  French Far East Expeditionary Corps.