Every major American war has produced at least one president, except Vietnam, the protracted, unpopular and still controversial war.
But if Sen. John Kerry or Gen. Wesley Clark have their way, that will soon change.
With the conflict in Iraq regularly claiming American sons and daughters and the threat of terrorism bringing Orange Alerts and shoe screenings at the nation's airports, voters have again made national security a top priority.
And the two Vietnam vets - the Lieutenant and the General - are emerging as the top contenders for that national security vote in the now wide-open and heated New Hampshire primary. Military experience gives both men special standing to criticize the president's handling of the war on terrorism without sounding weak on defense - a key to their appeal in the Democratic field.
But first, they must battle each other.
Kerry's come-from-behind win in Iowa puts additional pressure on Clark, who needs a strong New Hampshire showing to prove the viability of his candidacy. By opting out of Iowa, Clark had begun to show momentum here. But increased scrutiny of his record and Kerry's new strength has checked his rise in the polls.
"The big issue here is boiling down to who can beat Bush," says Jennifer Donahue of the Institute of Politics at St. Anselm's College in Manchester, N.H. "Their military experience may well be a motivating factor for many voters."
Kerry and Clark both regularly tout their military service and leadership. Both have small armies of veterans making calls, knocking on doors and standing proudly by them in the crowds. And both claim they've got the best credentials to win the battle to take on President George Bush - a man who avoided the draft by joining the Texas Air National Guard.
"George Bush thought he could play dress-up and prance around on an aircraft carrier," Kerry rails in a packed cafeteria at the Pembroke Academy here. "Well, if he wants to make national security a top issue, I want to remind him, I know something about aircraft carriers for real!"
While military service has never been a prerequisite for serving as the nation's commander in chief, it has long been a potent symbol of patriotism, sacrifice, and leadership that has helped propel men to the oval office, from General George Washington on.
But its salience is often dependent on the times. Bill Clinton, who acknowledged avoiding the Vietnam draft, beat two World War II veterans - George H. W. Bush and Sen. Bob Dole - in part because the country was at relative peace and economic problems loomed larger than perceived military threats. But even in times of relative calm, presidential candidates must prove to the voters they can be a strong commander in chief and deal decisively in foreign affairs, says Peter Feaver of Duke University. That was particularly true during the cold war and is again in the post 9/11 world. "The last time we had a candidate who won from Massachusetts, it was John Kennedy," says Professor Feaver. "He was able to convince voters that he'd be a strong commander in chief by running to the right of Richard Nixon on national security issues."
For decades, Republicans have had a lock on the so-called national security vote, and an even tighter grip on the military, where officers favor Republicans 8 to 1, and the enlisted 3 to 1, according to Feaver. Veterans, which make up almost 15 percent of the population, have also favored the GOP. Both Kerry and Clark are counting on their own experience and on dissatisfaction with the Bush administration among veterans to shift that dynamic - not a lot, but enough to swing a few voters in key districts in November when the race for the White House could be heated.
But first they must convince New Hampshire voters like Velia Poggi, who came to hear Kerry speak fresh from his Iowa win, that they can beat their rivals. "It matters to me if they're a veteran," she says "The fact that you've put your life on the line to defend the country, that gives you a special feeling for the country."
Ms. Poggi is leaning toward Kerry. But her husband, James, a World War II vet, is undecided and looking at Clark. "Military service is all well and good, but it's not decisive," he says.
In a video biography played to a packed Town Hall audience in Manchester, General Clark almost romanticizes his military experience. In his stump speech afterward, as if to make up for his deficit of domestic experience, he focuses mostly on economic issues, jobs and fairness, and beating back the special interests. But it's when he touches on national security, that he gets the most reaction. "[George Bush] promised us a humble foreign policy," Clark says, then increases his intensity: "Instead, he's alienated our allies, lost the respect of the world community, and cost 500 brave young men and women their lives!"
That brought the hundreds supporters to their feet to cheer at the old art deco Palace Theater.
In way, it's Clark's role as the ultimate military insider - the four-star general and supreme Allied commander in Europe - that allows him to criticize the President with a touch of impunity. But he's also playing to voters as a political outsider - the man who's free of special interests and old political baggage.
While Kerry is also a highly decorated veteran, he's playing somewhat as the military hero turned outsider, regularly mentioning his opposition to the Vietnam War, and long record of fighting the Pentagon for greater veterans' rights. As a four-term Senator, he is also a political insider - a role that has not always played well here in New Hampshire.