Question

When did the Nationalist resistance against colonialism develop in Vietnam?

Answer 1

 Ever since the minute vietnam was conquered by the French, there had been resistance, but organized independence efforts only began to take shape in the 30s to 50s, when leaders like Ho Chi Minh began to make themselves known and the rest of the empire began to be decolonized, leaving nationalist feelings simmering and French troop presence low. 

The Vietnamese also fiercely resisted the imperial Japanese army when they took over the province, and continued that feeling when the French took the reigns again.