Michael Joseph Mansfield (March 16, 1903 – October 5, 2001) was an American Democratic Party politician and diplomat who represented Montana in the United States House of Representatives from 1943 to 1953 and United States Senate from 1953 to 1977. As the leader of the Senate Democratic Caucus from 1961 to 1977, Mansfield was the second longest-serving party leader Senate history, after Mitch McConnell. During his tenure, he shepherded Great Society programs through the Senate. Born in Brooklyn, Mansfield grew up in Great Falls, Montana. He lied about his age to serve in the United States Navy during World War I. After the war, he became a professor of history and political science at the University of Montana. He won election to the House of Representatives and served on the House Committee on Foreign Affairs during World War II. In 1952, he defeated incumbent Republican Senator Zales Ecton to take a seat in the Senate. Mansfield served as Senate Majority Whip from 1957 to 1961. Mansfield ascended to Senate Majority Leader after Lyndon B. Johnson resigned from the Senate to become vice president. In the later years of the Vietnam War, he opposed escalation of American involvement and supported President Richard Nixon's plans for Vietnamization. After retiring from the Senate, Mansfield served as United States Ambassador to Japan from 1977 to 1988. Mansfield is the longest-serving American ambassador to Japan in history. Upon his retirement, he was awarded the nation's highest civilian honor, the Presidential Medal of Freedom. Mansfield later served for a time as a senior adviser on East Asian affairs to Goldman Sachs. (Wikipedia)