The president's Ho Chi Minh remarks weren't just a gaffe. His misreading of the Vietnam War impacts his judgment.

Whatever the opposite of a charm offensive is, President Obama is on it.

In Chicago on July 24, Obama delivered an hour-long speech in which he complained that “with this endless parade of distractions and political posturing and phony scandals, Washington has taken its eye off the ball.” The mother of one of the four Americans murdered at the U.S. diplomatic facility in Benghazi immediately objected. “He’s wrong. My son is dead. How could that be phony?”

A short while later, Obama was at it again.

Describing an Oval Office visit with the Vietnamese president Truong Tan Song, Mr. Obama reported: “We discussed the fact that Ho Chi Minh was actually inspired by the U.S. Declaration of Independence and Constitution, and the words of Thomas Jefferson.”

That assertion registered pretty high on the gaffe meter. Noted the editorial team at Investor’s Business Daily, “Few comparisons have been as odious as the one offered by the president linking one of the great mass murderers of history to one of America's Founding Fathers and authors of our liberty.”

It’s alarming when presidents engage in the practice of sloppy history—especially sloppy war history.

While Ho quoted the Declaration and Jefferson in his 1945 Declaration of Independence from the French, no reputable scholar of the Vietnam War would ever claim that he aimed to adopt American notions of a democratic civil society. Quite the contrary. His goal was to prevent the French from reestablishing their hold to Indochina once the Japanese were expelled. To that end, he did everything possible to ingratiate himself with the in-country American military advisors—and that included salting his declaration with cherished phrases from the American founding.

The advisors fell for it. Their “failure to identify Ho Chi Minh as Soviet-trained and a Communist ideologue,” Claude Berube wrote in a study of OSS operations, “was a major American intelligence shortcoming that smoothed the way for Ho’s emergence as a national leader and in the end, an enemy of the United States.”

But President Obama possesses more than a half-century of hindsight that those advisors could not. And getting that history right is as important to good governance as getting good intelligence.

The decisions we make that will affect our future are based very much on what we have experienced and what we think we know about the past. No matter how visionary or forward- looking a person may be, many of their judgments are based on history as they understand it. When our recollections of the past are faulty, it leads to even faultier judgments.

Many U.S. policy makers maintain that the Chinese decision-making is inscrutable and visionary. As proof, they often cite a 1972 exchange between Henry Kissinger and Zhou Enlai at the Paris Peace Talks:

Kissinger: Do you think the French Revolution was a success? Zhou: It's too early to tell.

Wow, that sounds profound. Except we have known for at least several years that Zhou thought Kissinger was talking about the Paris student riots in 1968—not the “let them eat cake,” guillotine-shadowed debacle that started in 1789. Zhou was a being an evasive politician, not a profound philosopher. Yet the story is still frequently told in Washington cocktail circles—and always with the wrong context.

Politicians are drawn to lazy history because it makes life easy for them. If they are wedded to the caricature of Chinese leaders as inscrutable deep-thinkers, a glib historical vignette can make their case…and provide an easy excuse for failure. After all, if the Chinese are inscrutable, no diplomat can be expected to “read” them properly, and no foreign policy can be expected to work as advertised.

The most serious case of such indolent history is the progressive view of the Vietnam War. Obama was barely out of diapers when Lyndon Johnson started ramping up the ground war. Yet, make no mistake, his understanding of the history of that war shapes his approach to today’s wars. “As President Obama was considering a deeper American commitment to Afghanistan,” wrote Marvin Kalb in The New York Times, “he would occasionally slip into an aide’s office, lean on his desk and wonder aloud whether he was making the same mistakes Johnson had made.”

In Obama’s history, Johnson’s failure was that he got roped into a long-term commitment. The fear of commitment led Obama to prematurely pull the plug on Iraq. It led him to opt for the light touch in Libya. It has made him pant for the zero option in Afghanistan. And it has moved him to exhibit zero interest in Syria.

But in following his self-taught history lesson of avoiding tragedy by avoiding commitment, he has adopted a tragically wrongheaded foreign policy.

After all the blood and treasure invested in Iraq, the premature U.S. pullout has given Al Qaeda and Iran a second chance to make mischief. The country just had its most violent month since 2007.

The massacre of Americans at the US consulate in Libya made that Obama effort the poster-child for the failure of on-the-cheap-foreign-policy.

In Afghanistan the White House is racing towards zero, while civilian deaths at the hands of the Taliban racing in the opposite direction.

And Syria is looking like an endless war.

Assuming that Johnson’s problem was fighting a long war is lazy history. Some long wars must be fought. Johnson’s problem was he fought a stupid war.

A less superficial history of the Vietnam conflict suggests that the progressive way of war is anything but the practice “smart” power. Johnson actually started out acting much like Obama, trying to do just enough to avoid being accused of doing nothing. This approach—doing as little as possible to get by—is called the “incrementalist” strategy.

The problem with an incrementalist approach is that the enemy pretty quickly figures out your strategy—and responds by incrementally and repeatedly upping the ante. Johnson got sucked into doing more and more until he was in too deep. Then he lacked the judgment to fight the war in a manner that would lead to a responsible conclusion.

The only difference between Johnson and Obama is that, in trying avoid being another Johnson, Obama is even more cautious and risk averse. In reality, however, he winds up in the same place—failing to defend U.S. interests and leaving the world convinced that America is in retreat.

When it comes to foreign policy, Obama’s sloppy history is feeding his penchant for failing often and early.

James Jay Carafano is vice president of defense and foreign policy studies at The Heritage Foundation.