CARLISLE BARRACKS, Pa. -- Officers studying at the Army War College walk the ground at nearby Gettysburg where Pickett's men walked across an open field under fire. They wonder, how did Confederate officers get men to do that? The lesson: Men can be led to places they cannot be sent.

Today's officers lead an Army that was sent into Iraq in 2003 and by 2004 the operation became, as an officer here says, "a deployment in search of a mission." Since then, missions have multiplied. Today's is to make possible an exit strategy. Gen. David Petraeus' Army/Marine Corps Counterinsurgency Field Manual says counterinsurgency's primary objective is to secure the civilian population rather than destroy the enemy. This inevitably involves the military in organizing civil society, a task that demands skill sets that are scarce throughout the government and have not hitherto been, and perhaps should not be, central to military training and doctrine. Nevertheless, the War College is coming to grips with the fact that what soldiers call "nonkinetic" -- meaning nonviolent -- facets of their profession are, in Iraq, perhaps 80 percent of their profession.

For soldiers, the tempo of change, technological as well as intellectual (and technological change is a driver of intellectual change), is accelerating. For centuries, nations assumed that they could be seriously threatened only by other nations; that terrorism was a weapon of the weak and therefore a weak weapon; that wars are won by large decisive battles.

America's Weinberger-Powell doctrine of the 1980s seemed vindicated in 1991 in Operation Desert Storm: Force should be used as a last resort, overwhelmingly and on behalf of clearly defined objectives. That doctrine was jettisoned in 2003, when forces less than one-third the size of those deployed in 1991 for the modest objective of liberating Kuwait were sent into Iraq to implement grandiose nation-building and democracy-implanting objectives.

Today, those who believe that Operation Iraqi Freedom was well-named and wise also believe that Petraeus' surge is succeeding and that criticism of Iraq's dysfunctional government is primarily a ploy by war critics to distract attention from that success. Petraeus, however, says his mission is to buy time for political reconciliation to occur. The recent National Intelligence Estimate said that although the surge is producing real if uneven security improvements, progress toward political reconciliation has been negligible and might be perishable. Hence the surge is a tactical success disconnected from the strategic objective it is supposed to serve.

Americans awaiting a report from the studious Petraeus should know that, as Maj. Gen. David Huntoon, War College commandant, says, Petraeus' intellectual qualifications (a Princeton Ph.D.) "are remarkable but not anomalous." The officers currently here -- 71 percent have served in Iraq, 34 percent in Afghanistan, many in both -- are doing something their civilian leaders did negligently five years ago -- thinking.

They think America needs, in the words of one officer, "an expeditionary capacity other than military." Officers here especially admire the introduction to the University of Chicago's edition of the Counterinsurgency Field Manual. Written by Sarah Sewall of the Kennedy School of Government at Harvard, it says:

We see in Iraq "military doctrine attempting to fill a civilian vacuum." In counterinsurgency, "nonmilitary capacity is the exit strategy," which is problematic when "more people play in Army bands than serve in the U.S. foreign service." Counterinsurgency "relies upon nonkinetic activities like providing electricity, jobs, and a functioning judicial system. ... But U.S. civilian capacity has proved wholly inadequate in Afghanistan and Iraq." The military is "in a quandary about the limits of its role" as it is forced "to assume the roles of mayor, trash collector and public works employer."

The Army has, and must have, a "can do" attitude. One of the things it must be able to do, however, is speak truth to America's civilian leaders about what it cannot do. "That," says one "can do" officer here, "goes against our military culture." But another participant in a freewheeling discussion stresses the importance of "communicating risks to our civilian masters."

One certainty is that America's enemies understand what kind of war -- protracted and inconclusive -- saps America's patience. An officer fresh from Afghanistan notes a Taliban axiom: "Americans have the watches but we have the time." Some officers here recently visited Appomattox to help them think about "war termination." Fortunately, thanks to the services' institutions such as the War College, America's remarkably reflective military services, their burdens promiscuously multiplied by civilians down the road in Washington, are up to another challenge that civilians have devolved to them: Thinking.