President Bush and other leaders bid goodbye to outgoing Defense Secretary Donald Rumsfeld at a full-honors ceremony on Friday.

Bush called Rumsfeld "one of America's most skilled, energetic and dedicated public servants."

"We've been through war together," the president said. "We have shared some of the most challenging moments in our nation's history."

Rumsfeld was a casualty of growing opposition to the war, manifested in the Democrats' takeover of Congress. Bush announced Rumsfeld's departure the day after Republicans were jolted in the November elections.

"I've never worked harder for a boss and I've never learned more from one, either," said Vice President Dick Cheney, who began his career in politics as an intern for Rumsfeld in 1969.

Cheney praised Rumsfeld as a man with "near perfect recall. He has the way of asking you the one question you are not prepared for. And apparently he does not sleep."

Gen. Peter Pace, chairman of the Joint Chiefs of Staff, said the 2.4 million members of the U.S. military joined in saluting "this incredible American, for his leadership and service to our country."

"He's a man of enormous commitment," Pace said. "He pushed us hard. The only person he pushed harder was himself."

A former Navy aviator, the 74-year-old Rumsfeld is the oldest defense secretary in U.S. history and the only person to have held the position twice. He was the youngest defense secretary when he began his first stint as defense chief in 1975.

When Robert Gates is sworn in as defense secretary on Monday, Rumsfeld will leave office just 10 days short of becoming the longest-serving ever, a distinction held by Vietnam-era Robert S. McNamara, who left under a cloud of another war gone awry.

Rumsfeld told the nation's service men and women last week on a surprise trip to Iraq that serving with them has been the "highest honor" of his life.