Andrew J. Bacevich is a professor of history and international relations at Boston University and a retired Army officer. An updated edition of his book “The New American Militarism: How Americans Are Seduced by War” will be published this month.

Judgments rendered by history tend to be tentative, incomplete and reversible. More than occasionally, they arrive seasoned with irony. This is especially true when it comes to war, where battlefield outcomes thought to be conclusive often prove anything but.

Rather than yielding peace, victory frequently serves as a prelude to more war. Once opened, wounds fester. Things begun stubbornly refuse to end. As the renowned strategic analyst F. Scott Fitzgerald once observed, “The victor belongs to the spoils.”

Next year marks the centennial of the conflict once known as the Great War. Germany lost that war. Whether France and Britain can be said to have won in any meaningful sense is another matter. Besides planting the seeds for an even more horrific bloodletting just two decades later, the fighting of 1914-1918 served chiefly to provide expansion-minded British politicians with a pretext for carving up the Ottoman Empire. It proved a fateful move.

What London wanted from this new Middle East that it nonchalantly cut and pasted was profit and submission; what it got was resentment and resistance, yielding a host of intractable problems that in due time it bequeathed to Washington. In effect, victory in 1918 expanded Britain’s imperial domain only to accelerate its demise, with the United States naively assuming the mantle of imperial responsibility (euphemistically termed “leadership”). Thank you, Perfidious Albion.

The USO’s new Warrior and Family Center is its largest facility yet and offers service members and their families what they said they needed most. From a theater and golf simulator, to meditation rooms and computer classes, videojournalist Zoeann Murphy gives us a look at the new facility through the eyes of wounded vets. (The Fold/The Washington Post)

Many another storied triumph has contained its own poison pill. More recent examples include the Six Day War, which saddled Israel with a large, restive minority that it can neither pacify nor assimilate; the ouster of the Soviet Union from Afghanistan, giving rise to the Taliban; and Operation Desert Storm, after which the garrisoning of U.S. forces in Saudi Arabia helped light the long fuse that would eventually detonate on Sept. 11, 2001.

Think you’ve won? Wait until all the returns are in.

With the passage of time, near-term military results matter less than long-term political consequences. Fifty years ago, when the Korean War ended in an apparent stalemate, most Americans considered Harry Truman’s “police action” a horrendous mistake. Viewed today, that brutal conflict may qualify as the most successful U.S. military action of recent decades. Consider what came next: a half-century of stability in Northeast Asia that allowed the Republic of Korea to emerge as a prosperous democracy and a loyal ally. Not too shabby.

Of course, that upbeat assessment pertains only if we define the U.S. objective as containing communism. In the autumn of 1950, the mission of U.S. forces pressing north of the 38th Parallel toward the Yalu River was rollback. Judged by this criterion, Truman’s war even today rates as a failure. The effort to liberate North Korea yielded little apart from a needless conflict with China — which prompted a chastened Truman to reinstitute containment as the principal U.S. war aim.

A challenge facing historians of the Iraq war, which began 10 years ago this month, will be to gauge what senior members of George W. Bush’s inner circle were actually trying to accomplish. The justifications offered for the invasion were all over the place, including supposed weapons of mass destruction, claims that Saddam Hussein had collaborated with al-Qaeda and visions of democracy throughout the Arab world. Eventually, only this last — Bush’s Freedom Agenda — remained. Yet, as the war dragged on, expectations of transforming the Middle East gave way to more modest definitions of success. When it came to advancing the cause of liberty, the Bush administration set out to build a cathedral. In the end, the Obama administration declared itself content with a shaky two-car garage.

Considered from this perspective, Sen. John McCain’s recent assertion that “history has already made a judgment about the surge” of troops in Iraq in 2007 — a statement meant to disqualify Chuck Hagel as defense secretary for having the gall to question the strategy at the time — qualifies as a nifty sound bite but is suspect on at least two counts. It is almost certainly premature. And more important, it is profoundly misleading.

Anti-government insurgents in Iraq continue to wreak havoc. U.S. forces may have left the scene — the troop surge facilitating their departure — but the conflict continues, its outcome yet undetermined. Granted, bombs blowing up in Baghdad now fall into that vast reservoir of facts that Washington chooses to ignore.

So what did the surge accomplish? With the Bush administration having long since given up on actually winning, the surge — in which 26,000 additional American troops were deployed to Iraq — saved the United States from having to acknowledge outright defeat. Gen. David Petraeus, who commanded the troops during the surge and became its public face, thereby provided an exasperated military with a feel-good moment and gave die-hard proponents of Operation Iraqi Freedom a chance to exchange fist-bumps. That they would savor the moment is perfectly understandable. But the moment was always destined to pass.

Recall when Richard Nixon, back in 1970, turned U.S. forces loose on Cambodia. Enormously controversial at the time, the offensive allowed frustrated troops a chance to get in some licks against an elusive adversary, while back home the Vietnam hawks thumped their chests. Yet any tactical advantage gained by going after North Vietnamese sanctuaries came too late to affect the war’s outcome. Ever so briefly, the Cambodian incursion seemed like a really big deal, Nixon himself calling it “the most successful military operation of the entire war.” That it may have been; but it settled nothing and soon faded to insignificance. I suspect that a similar fate awaits the surge.

The importance attributed to the surge by devotees such as McCain distracts attention from matters of far greater significance. It’s the equivalent of using the Battle of New Orleans as a basis for evaluating the War of 1812. Of course, in contrast to Petraeus, Gen. Andrew Jacksondefeated his adversary. When the shooting stopped, it was the surviving Redcoats — not the surviving Americans — who packed up and left. Still, take your cues from Johnny Horton, and you might conclude that Jackson single-handedly redeemed an entire war. Take your cues from McCain, and you might conclude that, two centuries later, Petraeus did likewise.

In reality, the heroics at New Orleans proved irrelevant to the outcome of the war, which the Treaty of Ghent had ended two weeks before. The most that can be said for Jackson’s victory is that it distracted attention from the egregious failures of political and military leadership that had marked James Madison’s War. So, too, for a time Petraeus’s victory (if that’s what it was) might do the same for George W. Bush’s War, likewise marred by glaring errors committed at the top. It’s the oldest technique in the campaigner’s playbook: Inflate a glimmer of good news to divert attention from all the bad.

With time, context changes, and with it, perspective. With all due respect to the various bicentennial commissions diligently attempting to convince Americans otherwise, the years have consigned not only the Battle of New Orleans but the entire War of 1812 to the sphere of things that no longer matter. (Okay, the nation got an anthem, but that’s about it.)

The political and military ineptitude displayed during the conflict did nothing to impede what turned out to be one of most momentous stories of the 19th century: the emergence of the United States as the richest and soon the most powerful nation in the world.

Sure, British troops ransacked the White House and burned the Capitol. So what?

I am prepared to speculate — unlike McCain, I make no claim of offering a definitive judgment — that, in its historical importance, the Iraq war will end up somewhere on a par with the War of 1812 (though without a comparable musical legacy). If not forgotten, it will be subsumed into a much larger story, remembered not as a big, important war but as a small, insignificant skirmish. Indeed, that process of diminishment has already commenced, albeit with an unwelcome twist.

In what has become one of the most momentous stories of the 21st century, the inhabitants of the Islamic world are asserting the prerogative of determining their own destinies. Intent on doing things their way, they are increasingly intolerant of foreign interference. In Iraq and Afghanistan, Washington sought to revalidate an altogether different prerogative, one pioneered by Britain: an entitlement to meddle.

To reaffirm that entitlement after Sept. 11, 2001, the United States sought to demonstrate its capacity to impose its will on its designated adversaries. The failure of U.S. forces to do that — to win clearly and unambiguously — calls any further exercise of that entitlement into question. More to the point, it suggests that the big story of Muslim self-determination is likely to continue unimpeded, whether Washington approves or not. Sure, American troops captured Baghdad and overthrew Saddam Hussein. So what?

Back in 1947, the promulgation of the Truman Doctrine kicked off Washington’s effort to put its imprint on the Greater Middle East, while affirming that Britain’s exit from the region had begun. U.S. power was going to steer events in directions favorable to U.S. interests. That effort now seems likely to have run its course. The United States finds itself today pretty much where the British were back in the 1920s and 1930s. We’ve bitten off more than we can chew. The only problem is that there’s no readily available sucker to whom we can hand off the mess we’ve managed to create.

Bacevich’s previous Outlook essays include:

Endless war, a recipe for four-star arrogance

I lost my son to a war I oppose. We were both doing our duty.

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