The continuous air campaign that the United States begun in March 1965 was Operation Rolling Thunder. It was the codename of one of the four major US bombing missions in the Vietnam war, that took place between 1 March 1965 and 1 November 1968.
The operation did not have the expected strategic effects, that is to put the resistance of the Viet Cong to its knees, razing at the nerve centers (military bases, bridges, communication systems, port areas, etc.). This was because the objectives set by the campaign were not as vital as the US staff felt, because the fighting method of the Viet Cong was based on the guerrilla war and they did not need any particular infrastructure or substantial supplies.