ARLINGTON, Va. -- Mike Mansfield was portrayed at his funeral as an American hero: an orphan-turned-soldier, an endearing diplomat, a politician who proved his could be a noble profession.

Mansfield, who served as Senate majority leader longer than anyone else and was the nation's ambassador to Japan for two presidents, was buried Wednesday in Arlington National Cemetery.

Mansfield died Friday at 98. In an hour-long service in a sunsplashed Army chapel, he was eulogized as a lawmaker who deflected praise even as his work left a lasting impression on the nation.

The Montana Democrat was majority leader from 1961 until he retired from the Senate in 1977.

He shepherded passage of the mid-1960s civil rights laws, Medicare, federal aid for college and the constitutional amendment that gave 18-year-olds the vote -- all controversial in a nation torn by Vietnam, race riots and the assassinations of the Kennedys and the Rev. Martin Luther King Jr.

"Mike Mansfield's leadership was the hinge of history," eulogized Charles Ferris, Mansfield's longtime friend and his legal counsel as majority leader.

Niece Stephanie Shea O'Connor remembered Mansfield, however, simply as "Uncle Mike." She recalled a childhood visit to the Senate 30 years ago when Mansfield plucked a carnation from a vase and gave it to her. She pressed the flower into a Dr. Seuss book.

"You are our giant, our hero," she said. "But you are also our Uncle Mike, who we will mourn and miss."

Diplomats, senators and generals were among the more than 400 people who attended the service, including Majority Leader Tom Daschle, D-S.D., and Senate Appropriations Committee Chairman Robert Byrd, D-W.Va. Yukihuko Ikeda, a former foreign minister of Japan, also attended.

President Bush ordered flags flown at half-staff at federal buildings around the nation.

As mourners sang "America the Beautiful," Mansfield's flag-draped casket was carried out of the chapel by uniformed pallbearers from each of the Armed service branches.

Mansfield was orphaned as a toddler and sent to live with relatives in Montana. He ran away at 14 and lied about his age to join the Navy and fight in World War I. Before he was 20, he also had served in the Army and the Marines.

He returned to Montana after the war to work in the copper mines. There, he fell in love with a schoolteacher named Maureen Hayes, whom he married.

Mansfield, whose wanderings through China as a Marine private planted the seed of his interest in Asia, became a professor of Far Eastern history after his wife persuaded him to return to school.

A Democrat, he was elected to the U.S. House and served five terms before being elected to the Senate. There, he eventually inherited a chamber divided by mistrust. His low-key style of patience and respect remade the Senate.

"He transformed the Senate from a Senate of power brokers to a Senate of equals," Ferris said. "He never twisted an arm, but he touched the conscience of his colleagues."

President Carter sent Mansfield to Japan as ambassador in 1977. When the White House changed parties, President Reagan asked him to stay, and he did, serving until 1988.

After retirement, Mansfield went to work as a Far East consultant for investment banking firm Goldman Sachs and Co.

Mansfield was buried next to the grave of his wife, who died last year.