Read more from Slate's Sept. 11 anniversary coverage.
Much has changed since the attacks of Sept. 11, 2001, but few American institutions have changed as much as the military.
At the most basic level, it has shifted from a peacetime military to a continuously wartime military, and it has done so for the first time since the United States got rid of the draft.
Just as dramatic is the type of wars that this professional, all-volunteer military—especially the Army—has been fighting. They're not the tank-on-tank battles that soldiers had been training for on the high plains of Europe. They're counterinsurgency campaigns, waged in towns and villages, in which junior officers must assume as much initiative as commanders, and in which all soldiers, even enlisted personnel, must be as attentive to community relations as to combat.
This is an adaptive, learning army, and its lessons have come not just from senior officers—such as the Counterinsurgency Field Manual, supervised by Gen. David Petraeus—but also from online networks (such as CompanyCommand.com and SmallWarsJournal.com). And many senior officers welcomed the trend, once they realized that the Web was being used not to air gripes or broadcast calls for insubordination but rather to exchange practical ideas about dealing with threats and challenges ("Here's how our company reduced the danger of roadside bombs …")—threats and challenges that no higher-ranking officers had experienced or Army field manuals had addressed.
In the summer of 2007, I wrote an article for the New York Times Magazine about growing tensions between junior and senior officers in the Army, stemming from the fact that many captains and majors had more combat experience—and more wisdom about the kind of war they were currently fighting—than many generals.
In the four years since, this situation has changed, in part because today's top generals earned their extra stars as ground commanders in these wars. Today, the Army chief of staff is Gen. Ray Odierno, who helped plan and execute the surge in Iraq. The chairman of the Joint Chiefs of Staff is Gen. Martin Dempsey, who was one of the war's most creative division commanders and an early adapter in counterinsurgency thinking.
Back then, many junior officers were upset that Col. H.R. McMaster, the commander of the 3rd Armored Cavalry Regiment who brought order to the Iraqi town of Tal Afar, was passed over for promotion to brigadier general. They saw the neglect as a signal that the Army establishment didn't value the kind of officer that McMaster represented. Later that year, the Army's promotion board went through an upheaval, to reflect the changing culture, and McMaster got his star. (Then again, he was recently passed over for promotion to two-star general, so the transition isn't complete.)
Huge changes have also taken place in thinking about tactics, strategy, and the very concept of warfare. In the '90s, many soldiers fought in Panama, Bosnia, Somalia, and Haiti—the sorts of wars that had once been called "small wars" or "low-intensity conflicts." But the top generals at the time, having suffered through Vietnam, were so averse to getting involved in these kinds of conflicts that they didn't even call these wars wars. They officially designated them "Military Operations Other Than War," or MOOTW, pronounced, with sneering contempt, "moot-wah." The JCS chairman at the time, Gen. John Shalikashvili, was known to have muttered, "Real men don't do moot-wah."
Now moot-wah is just about all that real men (and women) do in the Army, and nobody would claim that they're fighting in something "other than war."
These current wars also tend to be fought more flexibly and imaginatively (though, caution, that doesn't necessarily mean successfully) than before. In late 2001, after President George W. Bush decided to invade Afghanistan, Gen. Tommy Franks, the U.S. commander in the region, worked up a war plan that involved sending in two Army divisions through Pakistan. What wound up working, of course, was an innovative mix (put together mainly by the CIA) of spies, special-ops officers, and a new generation of "smart bombs" dropped from the air—all of which helped the Afghan militias, mainly the Northern Alliance, overthrow the Taliban government, long before either of Franks' two divisions began to be mobilized.
Secretary of Defense Donald Rumsfeld learned the wrong lesson from this expedition, believing that we could perform roughly the same trick in Iraq. The Army—again, Gen. Franks and his analysts—estimated that invading Iraq would require about 300,000 troops. But Franks was wrong about Afghanistan, so Rumsfeld reasoned that he must be wrong about Iraq, too. Rumsfeld sent in 130,000 troops and a lot of drones and planes carrying smart bombs. They were enough to smash the Iraqi army and topple Saddam Hussein—but not nearly enough to impose order afterward. (Ditto, by the way, for the small number of special-ops forces in Afghanistan.)
Rumsfeld was right that the GPS-guided smart bombs, high-tech sensors, and computerized communications networks—all installed in U.S. military units over the previous decade—altered the calculations of how many ground troops are needed to perform certain missions. Rumsfeld's problem was that he didn't care about Iraq after Saddam's ouster, which is to say he didn't (or didn't want to) understand Clausewitz's dictum that war is politics through other means—i.e., that a war is fought to accomplish some strategic objective and that, therefore, the war isn't over until the objective is accomplished. Some say that he "won the war but lost the peace," but that misstates the issue. The real problem is that he didn't finish the war.