Perhaps you should try some spelling variations:
"opponent of U.S. involvement in the Vietnam War" » "oponen of U.S. involvement in the Vietnam War", "oponente of U.S. involvement in the Vietnam War"
"opponents of U.S. involvement in the Vietnam War" » "oponens of U.S. involvement in the Vietnam War", "oponentes of U.S. involvement in the Vietnam War", "components of U.S. involvement in the Vietnam War", "exponents of U.S. involvement in the Vietnam War"
"component of U.S. involvement in the Vietnam War" » "componente of U.S. involvement in the Vietnam War", "components of U.S. involvement in the Vietnam War", "componen of U.S. involvement in the Vietnam War"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (((("opponent of U.S. involvement in the Vietnam War") OR ("opponents of U.S. involvement in the Vietnam War"))) OR ("component of U.S. involvement in the Vietnam War"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"opponent of U.S. involvement in the Vietnam War\") OR (\"opponents of U.S. involvement in the Vietnam War\"))) OR (\"component of U.S. involvement in the Vietnam War\"))*".
• Removing quotes may allow a broader search: (((( opponent of U.S. involvement in the Vietnam War ) OR ( opponents of U.S. involvement in the Vietnam War ))) OR ( component of U.S. involvement in the Vietnam War ))*.