Do you know if there was a Democratic-controlled Congress at the onset of the Vietnam war?
The war started as an insurgence against the French colonialists. US involvement started under the rule of Lyndon B. Johnson, a democrat. Kennedy went on and Nixon, republican, finally ended it as the length of the war, the high number of U.S. casualties, and the exposure of U.S. involvement in war crimes such as the massacre at My Lai helped to turn many in the United States against the war.
Check it at
http://www.encyclopedia.com/html/section/VietnamW_U.S.Involvement.asp