Kerry's Vietnam record caused controversy in the 2004 US elections [Gallo/Getty]
War is the supreme test of man in which he rises to heights never approached in any other activity.
- General George Patton
La guerre! C'est une chose trop grave pour la confier a des militaires. (Trans: War is too serious a matter to entrust to military men.)
- George Clemenceau
More than two and a half million Americans served in the Vietnam war between 1960 and 1973.
About one and a half million of those either fought in combat or were regularly exposed to attack by North Vietnamese and Vietcong forces.
And 58,000 Americans did not return alive.
But not a single one of the (overwhelmingly) men who fought in Vietnam and returned home has become president.
This election marks the first - and probably the last - time a Vietnam veteran could become America's chief executive.
John McCain not only served in combat - he flew 23 combat missions - but also endured more than five years of captivity as a prisoner of war in North Vietnam, during which time he and his fellow prisoners say they were repeatedly beaten and tortured.
McCain has made his Vietnam experience the central pillar of his personal narrative and his political career.
But most Vietnam veterans turned politicians have not parlayed their experiences as successfully as McCain.
Bill Clinton, the first Vietnam-era baby-boomer to run for the White House, famously avoided getting drafted by dint of various student deferments, delayed medical checks and a letter in which he thanks a draft board officer for "saving" him from military service.
Clinton's draft record earned him furious hatred from many right-wing conservatives, but apparently did not bother the electorate enough to prevent them from giving him two terms as president, both times defeating decorated second world war veterans - George H W Bush and Bob Dole.
Al Gore actually served on the ground in Vietnam. Although Gore opposed the war, he enlisted in the US army in 1970 and spent five months in Vietnam in an engineering battalion and as a military journalist.
|Bill Clinton's draft record came under scrutiny in the 1990s [AFP]
But he did not see combat or come under enemy fire and Gore lost the 2000 race to George Bush, who was a member of the Texas air national guard during the war.
Bush has always dismissed reports that he received special treatment in jumping ahead of others on a waiting list to join the guard, membership of which meant that he would not be sent to Vietnam.
Some of the circumstances surrounding his military service remain murky.
John Kerry's Vietnam war record paradoxically became a liability in his unsuccessful attempt to oust Bush in 2004.
Republican operatives spread stories accusing the multi-decorated Kerry of lying about his Vietnam record and even pretending to be wounded in order to receive a medal.
Grinning delegates at the Republican party convention in New York wore little bandages on their faces to mock Kerry, implying he had only been scratched, not wounded.
The scurrilous charges were refuted by Kerry’s wartime companions and the official Pentagon record, but his mishandling of the charges allowed the "Swift-Boat Veterans For Truth" to damage him.
The Vietnam war record of the Bush administration's most ferocious hawk is more clear cut.
Dick Cheney, the US vice-president, was a supporter of the war, but when he became eligible for the draft, he applied for and received five consecutive deferments, including several college deferments.
Cheney's college career lasted six years instead of the customary four and his final deferment was granted when his wife became pregnant.
Cheney told a Washington Post interviewer in 1989, when he was about to become secretary of defence, that "I had other priorities in the 60s than military service".
Before Vietnam, military men stood a pretty good chance of becoming president, starting with the first and one of the best of them all, George Washington.
Thirty-one of the 42 US presidents have been veterans, and every presidential election since the second world war has featured at least one veteran on the final ballot.
Americans have often welcomed top military brass into the White House. Twelve presidents, including Washington, were generals.
The benefits of electing a general as president, however, are unclear.
Dwight Eisenhower did a decent job of ending the Korean war and leading the country through the darkest days of the Cold war.
Upon his departure from office, Eisenhower left Americans with a powerful and prescient warning: "In the councils of government, we must guard against the acquisition of unwarranted influence, whether sought or unsought, by the military-industrial complex.
"The potential for the disastrous rise of misplaced power exists and will persist."
Ike, we should have listened to you!
Andrew Jackson was one of the most powerful 19th-century presidents.
His great military distinction was to lead a ragtag force of US army regulars, Louisiana militiamen, freed slaves, and French pirates who soundly defeated an elite British army at the Battle of New Orleans in 1815.
On the other hand, Ulysses Grant was a great general, whose relentless tactics crushed the Confederacy and ended the civil war (and slavery).
|Ulysses Grant: Great general, poor president? [GALLO/GETTY]
But he was by all accounts a lousy president, who allowed congress to lead and whose administration was rife with scandals.
And several of our general-presidents hardly spent much time as president at all.
Zachary Taylor fought the British in the War of 1812 and in various attacks meant to take away the land belonging to indigenous tribes and facilitate white settlement.
He died 16 months after becoming president.
James Garfield was a genuine civil war hero, having commanded troops in some of the most vicious encounters of the war at Shiloh and Chickamauga.
But he had been in office barely a year when an assassin's bullet struck him down.
Short and sweet
The shortest presidency of all was William Henry Harrison's - the Indian-fighting general known as "Old Tippecanoe" in honour of his victory over native warriors led by Tenkswatawa, the Shawnee Prophet.
Even though Harrison's forces greatly outnumbered the Native Americans and suffered more casualties, he was hailed as a great national hero.
Running as the candidate of the now-defunct Whig party, Harrison's 1840 campaign slogan, "Tippecanoe and Tyler Too!", became one of the most famous in American political history.
Harrison beat Martin Van Buren in a particularly nasty campaign. His inauguration speech delivered on March 4, 1841, remains the longest on record, and was delivered on a bitterly cold day as Harrison, hatless and without a winter coat, stood orating for almost two hours.
Shortly afterwards, the 68-year-old Harrison caught a cold, which rapidly flared into pneumonia.
Despite - or more likely, because of - the application of the very latest in American medical science, including doses of opium and Virginia snakeweed, and even, according to some accounts, actual snake-bites, Harrison was dead exactly a month after being sworn in.
In more recent times, Republicans have consistently been able to portray Democratic presidential candidates as "weak" on leadership, national defence, and military issues - even when, as in the case of Kerry or 1972 candidate George McGovern, those candidates were decorated war heroes.
In the current election cycle, polls show many voters remain sceptical of Barack Obama's abilities to be a good commander-in-chief, while a much larger number say McCain would be a good commander.
That is one of the reasons why, despite widespread disenchantment with the Republican party, deep disapproval of George Bush, and a bumbling campaign, McCain continues to compete with Obama.
In fact, however, it has been presidents with little or no military experience who have led this country through its darkest hours.
|Many voters remain war of Obama's commander-in-chief abilities [EPA]
Abraham Lincoln never went to a military academy; he spent a couple of months in the Illinois militia during a forgettable incident known as Black Hawk's war.
But in the bloodiest war in American history, he proved an adept commander and an effective leader.
Franklin Roosevelt never wore a uniform, but he prevailed in the titanic struggle to defeat Hitler and imperial Japan.
Regarding military men as president, history's message is muddled.
But what is clear is that the next president - whichever of the two men he proves to be - will inherit two wars and a tense and profoundly dangerous international situation regarding Iran, the Israeli-Palestinian conflict, and the potential for attacks by non-state actors such as al-Qaeda.
The country, and the world, will need a leader with a calm and steady hand.