Vietnam War

Based on my research, America fought in Vietnam to hold the line against the spread of world communism. America  paid for the war the french fought against communist as a part of the Truman Doctrine.By the 1950s american involved when the war flared up again. Americans later on developed the domino theory as a justification for the involvement. The Domino theory was a reason for war during the 1950s to 1980s ,promoted at times by the government of the United States.It was the thought of if one state in a region came under the influence of communism,then the surrounding countries would follow in a domino effect.The movement against the involvement of the united states in the Vietnam war began in the U.S. with demonstrations in 1964 in grew in strength later years.The U.S became separated between the people who wanted the involvement continued in the Vietnam war and the people who only wanted peace.  

http://en.wikipedia.org/wiki/Vietnam_War

http://www.learnhistory.org.uk/vietnam/reasons.htm