As Newt Gingrich will be the first to tell you, he is a man with a vast and deep résumé. One boast he has been offering lately makes the former House speaker and current presidential contender sound like a cross between Mr. Chips and Sun Tzu.

“I am the longest-serving teacher in the senior military, 23 years teaching one- and two-star generals and admirals the art of war,” Gingrich said at the most recent GOP presidential debate in Iowa.

That’s a grandiose way of describing a guest-lecturing gig, which is what Gingrich used to do twice a year for the Joint Flag Officer Warfighting Course, a seminar for promising young generals and admirals at Maxwell Air Force Base in Alabama.

“He has typically lectured from 2-4 hours on the topic of military/political affairs,” military spokesman Phil Berube explained in an e-mail. “Available records show he has lectured 20 times going back to 1996, more than any other non-government employed civilian invited to speak.”

There is no disputing Gingrich’s enthusiasm for the subject, or how much effort he has put into styling himself as a commander-in-chief-in-waiting.

Although Gingrich is mostly known for political warfare, few people in the world of politics have understood that war itself has long been a preoccupation for this former history professor and Army brat.

Mostly behind the scenes, Gingrich has found a place in an inner circle of military leaders, acting as teacher, consultant and thinker. This has allowed him to exercise a part of his character that even his critics say is appealing — his ability to come up with big ideas.

Several former officials said the nature of daily life at the Pentagon — the firehose of decisions, information and duties — created an appetite for Gingrich’s longer-term, high-altitude perspective. It was a great fit for the former House speaker, who was trained as a historian and has seen himself simultaneously as a futurist.

Even after he left Capitol Hill in 1999, Gingrich’s ideas were welcome, Pentagon officials said, even if they weren’t often implemented.

“We took him seriously, because he had a kind of multifaceted claim on people’s attention,” recalled Douglas J. Feith, who was undersecretary of defense for policy from 2001 to 2005. “He had his practical government experience as speaker, which is a rare credential, and he had a lot of historical knowledge. He also had a lot of interest in executive matters.”

Following the attacks of Sept. 11, 2001, and in the difficult early years of the Iraq war, “he was willing to help. And at that point, we were looking for all the good ideas we could get,” added Lawrence Di Rita, who was Pentagon spokesman at the time.

Gingrich’s name appears on 19 declassified memos written by then-Defense Secretary Donald Rumsfeld, often passing along Gingrich’s thoughts to fellow George W. Bush administration officials or top military officers.

At the time, Gingrich was serving on a prestigious panel known as the Defense Policy Board Advisory Committee, an assignment that gave him an avenue to weigh in on a wide variety of topics. It also was a role in which he could be a font of ideas, which has always been his strength, without actually having to execute them, a process at which he is not so skilled.

Among Gingrich’s suggestions were proposals to make military health care more efficient, privatize its postal system and coordinate more closely with the State Department in Africa.

As public opinion was turning against the Iraq war in 2005, Gingrich typed a four-page, 18-point plan urging Rumsfeld: “In the immediate test of will, we need to use whatever level of force is necessary to impose our will on [Sadr] and on Fallujah and we need to do it quickly before European and world opinion can block us.” The defense secretary forwarded it to Gen. John Abizaid, the head of Central Command, asking him to read it “and see how his ideas track with our thoughts.”

Some of Gingrich’s private memos to Rumsfeld foreshadow the stark and politically divisive national security positions that he has taken in his presidential campaign, including his frequent assertion that radical Islam is the greatest threat facing the country.

In a July 2003 paper for Rumsfeld that he called “Seven Strategic Necessities,” Gingrich warned against getting “drawn into a day to day incident managing, news media and legislator appeasing mindset” and called for deepening the political divide against “those who would hide and ignore reality (essentially the McGovern-Dean Democrats).” That was a reference to 1972 Democratic presidential nominee George McGovern, and former Vermont governor Howard Dean, the antiwar candidate who at that point was leading the 2004 Democratic presidential field.

Rumsfeld, who declined to be interviewed for this story, frequently suggested that others in the administration seek out Gingrich’s advice.

“It is pretty clear there has to be a new entrepreneurial model of nation building,” the defense secretary wrote in an April 22, 2002, memo to then-Vice President Dick Cheney. He added, “It strikes me that it would be useful to get some folks thinking about this. Newt Gingrich has some good ideas on this subject, as does [Peruvian economist] Hernando de Soto, who has been working some in the Arab world.”

Also copied on Rumsfeld’s memo urging Cheney to consult Gingrich were Secretary of State Colin Powell, Treasury Secretary Paul O’Neill, central intelligence director George Tenet and national security adviser Condoleezza Rice.

Gingrich’s national security approach occasionally put him at odds with the neoconservatives who ran foreign policy during the Bush administration.

Shortly before resigning his speakership, Gingrich had convinced then-President Bill Clinton to set up a bipartisan commission to develop a national security strategy. It became known as the Hart-Rudman commission, after the two former senators who chaired it, Warren Rudman (R-N.H.) and Gary Hart (D-Colo.). Gingrich himself was also appointed to it.

The commission warned that the nation was becoming complacent against terrorism — a view that, to its critics, looked like a loss of faith in America’s global power. Lynne Cheney, wife of the future vice president, quit the panel in 2000 because she disagreed with some of its findings.

In a scathing May 2000 story headlined “Newt Gingrich’s Last Boondoggle,” the neoconservative Weekly Standard derided the commission as Gingrich’s “pet rock,” and wrote that it was “something of a joke on the taxpayer almost since its inception.”

But though its recommendations in February 2001, were largely ignored, they were soon proven to be prescient. Among its proposals, for instance, was the creation of a new National Homeland Security Agency to consolidate and coordinate the various government departments with a role in protecting the country from terrorism.

Six months before the attacks on Sept. 11, 2001, Gingrich testified before the House Committee on Armed Services: “Terrorism is a much more profound threat than we have responded to,” he said. “It should trouble every American that we’ve been trying to get [al- Qaeda leader Osama] bin Laden since 1993. ... We should all be concerned that we don’t have the intelligence to know where they are, the ability to preempt or the capacity to punish.”

Gingrich’s closest military adviser has been retired four-star Gen. Charles G. Boyd, a highly decorated Air Force pilot who had spent nearly eight years as a prisoner of war in Vietnam. As it happens, Boyd — whose posts included command of the Air Force’s Air University — had first gotten to know Gingrich in the mid-1980s, when he was a student in one of the courses that the former speaker now talks about on the campaign trail.

“I have no idea, frankly, who discovered this young congressman and brought him down to teach a course there. But he lectured for four hours, a full half-day, with no notes, by the way. It was a tour de force that frankly impressed all of us,” Boyd recalled. “It was clear that he had a broad and deep understanding of the political world and the military world and how the two had to come together in some cohesive way, if the nation was going to execute its national security policies effectively.”

Gingrich also urged the military to shed its luddite inclinations in favor of new technologies and more efficient techniques.

“He was into [total quality management] and all that sort of thing at a time when the military was not,” Boyd said. “He was talking just-in-time logistics when some of the military services hadn’t figured out bar-coding yet.”

There is no evidence that Gingrich ever felt the personal inclination to serve in the military.

“He’s probably as aggressive with the military as anybody,” Rep. Ron Paul (R-Tex.), one of Gingrich’s Republican opponents, said on Fox News recently. “He supports all the wars in the Middle East a thousand times more than I would. But you know in the 1960s, when I was drafted in the military, he got several deferments. He chose not to go. Now he’ll send our kids to war.”

Gingrich’s adoptive father Bob Gingrich, a retired Army officer, told PBS’s “Frontline” during the mid-1990s that he had never regarded his son as military material.

“He is very nearsighted. You probably know that he can barely see across the street without his contacts. He has two of the flattest feet that there ever was,” his father recalled.

But maybe the field he chose wasn’t so different after all. The overview of Gingrich’s lecture to the Joint Flag Officer Warfighting Course in 2009 included this quote from Carl von Clausewitz, the famed Prussian military theorist of the 19th century: “War is politics by other means.”