MacDonald was the only senior Western official who was on the scene in Southeast Asia for those nearly ten critical years, drafting dispatches for the novice U.S. ambassador in Saigon (once the post was established) and profoundly influencing the Americans. No French politician or general, no American congressman or admiral, comes close to having his impact on the U.S. decisions that led America step by step into Vietnam. Perhaps that can be debated, but to write an 864-page book about the origins of America’s war in Vietnam, as Logevall did, and not know of MacDonald, with nary a mention, is like an historian writing of the early days of America’s war against Japan without noticing Douglas MacArthur.

A U.S. Military Assistance Advisory Group soon arrived in Vietnam, but the expressway kept going beyond Saigon, and it went onward to Baghdad and Kabul. 

THE CORRECTIONS above are just a sample for 1945–1950 but oblige us to ask why leading students of diplomatic history get so much wrong. 

 First is the temptation to write backward. Because America has long been a superpower, it’s easy to assume it became one right after history’s greatest war. Because of its industrial heft and atomic monopoly, surely it could affect events in vast colonized “developing” lands. Similarly, because the British Empire ended sometime after the war, and because of Britain’s financial crises, the Empire must have been “liquidated” in the thousand days after August 1945 due to “destruction at home” as America took over. Another eminent professor of history, Andrew Roberts, distills prevailing wisdom in an essay titled “Becoming the World’s Policeman.” An “exhausted Great Britain,” he writes, “handed on the baton to the United States,” and did so in 1947. Fantasies of batons and policing derive largely from that year’s over-the-top American headlines and from a hyperbolic bestseller of 1955, by which time the jig truly was about up for colonial Britain (The Fifteen Weeks: A Dramatic and Revealing Account, from Inside the Government, of the Momentous Days in Which We Assumed World Leadership). Why go deeper? 

Second, Pulitzer-winning memoirs by Dean Acheson and George Kennan have dazzled historians as well as journalists. Acheson’s embellishments are generally harmless, and his friends joked about what he’d left out. Kennan’s memoirs are different because of their grave, self-serving distortions, starting with the word count of his telegram. His exaggerated reputation comes from literary men and women—like professors and pundits—who make false assumptions about one of their own. Because Kennan himself proved to be such a good historian and essayist after leaving the government in 1953, he must have excelled while in office. So he stays an unimpeachable source. In contrast, John Wesley Snyder, like his friend Marshall, never wrote a memoir and kept the press at a civil distance. 

Third, few writers of American foreign relations are familiar with business, economics or technology. Or they become distracted by big-picture politico-military dramas. It’s unusual to delve, say, into the dusty details of the U.S. Treasury Department, which can be trickier to grasp. At the same time, historians get themselves entangled with contemporary affairs, like “national security” which has become as much an academic field as a field of practice. Both fields, however, are heavy on opinion (i.e., What might deter Iran?), and less so on rigor like physics or languages. Faculty members are seduced by the excitements of “security studies”—advising government, editorializing on TV—at the price of lasting scholarship. Roberts, for example, made himself a persuasive voice in 2003 for the policing of Iraq, including in the ears of President George W. Bush; Gaddis, while directing Yale’s international security program, concluded a year after the invasion that “the various parts of the strategy interconnect with each other in a fairly impressive way.”

Except Americans rarely do strategy, as four failed wars might indicate. Historians should know it and blow the whistle. 

What passes for considered policy is instead a twisting sequence of ad hoc decisions hammered out under the stresses of sudden foreign urgencies and heavily politicized responses. Why would it be otherwise given America’s freewheeling mode of policymaking, particularly in foreign affairs?

Meanwhile, legends of wisemen and a foreign policy golden age remain. President Kennedy’s “action intellectuals,” as described by journalist Theodore White, would regard themselves as heirs. After the Cold War, with America as the sole superpower, it wasn’t hard to assume we could remake the world, or at least “realign” and “transform the Middle East,” with a “dream team” War Cabinet in place. A certified wise man like Kissinger provided guidance in the runup to Iraq, as he has done recently about Afghanistan. “Munich!” reverberates in cries for action and the use of analogies—a primitive way to reference history—becomes part of the national style of policymaking. Huge and amorphously expanding objectives are rationalized. Every crisis heralds the next hinge moment of fate.

Disregarding the history of our opponents enables a deputy secretary of defense (formerly a professor of international relations at Johns Hopkins) to explain in 2004 that any differences between Sunni and Shia in Iraq were “exaggerated.” Vagueness about the past encourages us to believe in quick, easy high-tech solutions like computer-laden netcentric capacities in today’s forever wars. Is much said that helicopters were also expected to provide an easy win in Vietnam, like B-29 Superfortress bombers were in North Korea? America’s insularity is also forgotten as we exaggerate our ability to affect faraway places, which we don’t bother to understand. 

Ultimately, an explicit desire “to look forward as opposed to looking backward,” which President Barack Obama preferred, results in Americans forgetting their worst behaviors. Officials who, after 9/11, practiced torture in the service of the United States weren’t held to account, and now remain in the talent pool for high appointments. Another Johns Hopkins professor, Eliot Cohen, who writes on contemporary U.S. history and also held high office following 9/11, reflects on what he calls “lesser forms of torture,” such as waterboarding. He believes, despite all evidence, that it “probably yielded useful information.”

Historians of American foreign relations—like many journalists who write of war and national security since 1945—have succumbed to intellectual lethargy, much like Washington’s foreign policy community has succumbed. The callings of history and “national security” become intertwined, and not to the advantage of historical integrity. Mistakes of fact about how we got from there to here prove impervious to correction. So, choose any predicament that Washington labels a “crisis” and watch habits unfurl—many of which stem from misremembering what America lived through not long before.

Derek Leebaert is author of Magic and Mayhem: The Delusions of American Foreign Policy from Korea to Afghanistan, among other books. He was a founding editor of International Security and is a cofounder of the National Museum of the U.S. Army.