The United States of America failed to "save" South Vietnam from communism for various reasons. The approach the United States took to solve the situation in Vietnam was completely wrong. The struggle cost 3.2 million Vietnamese lives, two million Lao and Cambodians and nearly 58,000 American lives. They were misguided and misjudged the entire situation which eventually led to South Vietnam falling to communism.
After the French Indochina War, which lasted from 1946 to 1954, Vietnam was provisionally divided into North and South Vietnam. Ngo Dinh Diem feared he would lose hold of his regime declared the south an independent republic in 1955. South Vietnam is a densely populated area of around sixteen million citizens. Diem received American support because he was a devout catholic and hated communism. Although he had a history of poor human rights during his rule, anyone who was anti-communist was likely to receive US aid.
North Vietnam also had a population of sixteen million citizens. Those living in North Vietnam were controlled by the Vietnamese communist that fought against the French and aimed to reunify Vietnam under communist rule. The agricultural nation was supplied mainly with weapons from China. Guerillas were trained by the Viet Minh to go to South Vietnam and help spread the word of communism. To much surprise, the guerillas sent did not terrorize citizens in the south but were helpful and lent helping hands. This helped win over the "hearts and minds" of citizens in the south, making them more willing to help the guerillas in return. The Viet Minh appealed to the people because they not only wanted to fight for national independence, they were also fighting for social and political reform. Most search and destroy missions were carried out in helicopters. This detached the American troops from the citizens.