Asked how Americans should view the steady stream of body bags returning from Iraq, Rumsfeld responds: "Every person who is killed or wounded is a heartbreak, certainly for me and for their families and for their loved ones."

But he points out that the American casualties had all signed up for war.  "In this conflict every single person is a volunteer …  Every person there put their hand up and said, 'Send me, I want to participate in the defense of our country.'"

While the world may change, Rumsfeld is a constant.  He has been known throughout his 71 years as a problem solver who thrives on risk, confrontation and absolute control.  He is smart, energetic, combative, at times ruthless, but he can also be charming.

ABCNEWS' John McWethy sat down with the defense secretary for a series of no-holds-barred interviews at the Pentagon and at his New Mexico ranch to talk about his policies and personality.

Watch ABCNEWS' John McWethy's hourlong special on Defense Secretary Donald Rumsfeld on Primetime tonight at 10 p.m.

Never Standing Still

An interview with the defense secretary is a challenge.  Rumsfeld is a man in constant motion.  He rarely sits, even in his own spacious office at the Pentagon — where there is no chair at his desk.  "I stand here.  I use the phone," he told ABCNEWS.  "I like to.  Have for decades.  It works."

He wears a pedometer on his belt — to count every step he takes.  He tries to walk 10,000 paces a day, about five miles.

The pedometer is part of Rumsfeld's extreme attention to detail: counting, obsessing, analyzing . It's how he solves problems.  That devotion also frames how he lives his life.

Over a lifetime in business and politics, the defense secretary has developed his own "code of conduct," which he refers to again and again.  He calls the guidelines "Rumsfeld's Rules."

‘Not Too Long in This World’

One of Rumsfeld's rules is "If you are not criticized, you may not be doing much."

When Rumsfeld worked in the White House three decades ago, he defied President Richard Nixon by refusing to give speeches supporting a war in Vietnam that was going sour.

In a secretly tape-recorded conversation in the Oval Office, Nixon can be heard telling his top aide H. R. "Bob" Haldeman that Rumsfeld needs to go.

"But on Rumsfeld, we've done a hell of a lot for Rumsfeld.  I think Rumsfeld may be not too long in this world," Nixon said.  "Let's dump him."

Rumsfeld was never dumped, though.  And when Nixon resigned in disgrace, President Ford made him his chief of staff and then, in 1975, his defense secretary.  At 43, Rumsfeld was the youngest secretary of defense in U.S. history.

After Ford lost the 1976 election to Jimmy Carter, Rumsfeld entered the private sector, where he worked for the next 25 years.  He was a sensational success, turning failing companies into winners and turning himself into a rich man with a personal fortune of more than $100 million.

A Tough Boss

Vice President Dick Cheney says of Rumsfeld, "If he wasn't breaking china, he wouldn't be doing his job." 

The two have been close friends for 30 years.  But it did not start that way.  When they first met in 1969, Rumsfeld was a young congressman, while Cheney was a graduate student who wanted an internship. 

"He looked on me — I think properly — as an airy-headed academic and I looked on him as a very arrogant, young, abrasive member of Congress.  The interview lasted about 20 minutes and I left," Cheney told ABCNEWS.

That time, Cheney did not get the job.  But a few months later, when Rumsfeld left Congress to work in the Nixon White House, he finally hired the eager young Cheney.

"I walked into his office.  He sat at his desk and never looked up.  He never said, 'Do you want the job?' or 'I'd like to have you come and work for me,'" just "'You, you're congressional relations.  Now, get the hell out of here.'"

Cheney says Rumsfeld "was probably the toughest boss I ever had, but he probably taught me more than anybody I ever worked for.  He was very demanding.  He didn't have a lot of time to say 'thank you' or 'good job.'  The reward for doing a job well was you got more work."

Rumsfeld's style has not changed.  Retired Marine Corps Lt. Gen. Greg Newbold, who worked for two years under Rumsfeld, says the defense secretary at times "absolutely" could be abusive and brash.

Rumsfeld acknowledges his brusqueness: "I tend to be impatient.  So there's no question but that from time to time I help people understand the difference between good work and poor work."

Interference Allowed

However, Rumsfeld's management style became a major issue in the run-up to the Iraq war.

John White, who was Secretary of the Army at that time, said Rumsfeld micromanaged what the military calls deployment: determining exactly which troops would go and exactly when they would leave.

He charges Rumsfeld's interference caused troops to arrive in Iraq without equipment, and crucial support units to be weeks late in getting there.  "I would argue he was not part of the cure.  He was part of the problem," White said.

Rumsfeld argues that the military's deployment scheme was flawed, saying "it wasn't the way it should have been done and it is not the way it'll ever be done again."  But he adds: "If there are people who are disturbed about that, so be it."

To minimize the U.S. presence in the volatile region, Rumsfeld insisted on a much smaller force to fight the war than some of his generals wanted.  So when U.S. forces arrived in Baghdad after one of the fastest advances in history, there were not enough troops to stop what happened next. 

"We didn't have enough troops, enough boots on the ground, to stop the looting, to stop the wholesale destruction of the infrastructure of the country that we're now asking the American taxpayers to pay for," said White.

Rumsfeld argues he was just following another of his rules: "Reserve the right to get into anything — and exercise it." 

Discretion Valued

Three years ago, when Rumsfeld took the job as President Bush's defense secretary, he was already haunted by a premonition that the United States would be the target of a surprise attack.

At his Senate confirmation hearing on Jan. 11, 2001, he talked about the lessons of Pearl Harbor.

"There were plenty of signals, plenty of warnings, plenty of cautions, but they weren't taken on board.  They didn't register," Rumsfeld said.  "We've got to be wiser than that."

Then, eight months to the day after his warning of a surprise attack, Rumsfeld's fears became reality with the Sept. 11, 2001, terrorist attacks.

The months that followed sent his popularity and influence soaring.  He was videotaped helping move the injured from the stricken Pentagon.  The war in Afghanistan was widely supported.  Bush called Rumsfeld "my administration's matinee idol for seniors."

His profile was raised so high that intelligence sources say he and his family were stalked by terrorists who at least once tried to kill him.

So it was hard to argue with the defense secretary when he began to make the case for war against Iraq.

In August 2002, he told ABCNEWS in another exclusive interview: "We know what their intent is and we know that for certain.  So we know that the weapons [of mass destruction] exist, we know they're available, and we know anyone who listens to Saddam Hussein's video knows precisely what he has in mind."

Asked if he has had any second thoughts about the arguments he made to President Bush to invade Iraq, Rumsfeld said: "I don't talk about my advice to the president."

"Never talk about the advice you give the president."