The lessons of a new Army Field Manual.

Two messages flutter between the lines of the U.S. Army's new field manual on counterinsurgency wars, its first document on the subject in 20 years.

One is that Pentagon planning for the Iraq war's aftermath was at least as crass, inattentive to the lessons of history, and contrary to basic political and military principles as the war's harshest critics have charged.

The other is that as a nation we may simply be ill-suited to fight these kinds of wars.

The field manual's chief authors—Lt. Gen. David Petraeus and retired Col. Conrad Crane—would never make these points explicitly. When Petraeus was commander of the 101^st Airborne Division in Iraq, he combined combat power and community-building more astutely than any other officer. Crane, director of the Army's Military History Institute, is one of the leading scholars of "irregular warfare." They both support the war's aims. And they outline their new doctrine—or, rather, their revival of a very old doctrine—very thoughtfully and thoroughly.

Yet the undertone of this 241-page guidebook—not yet publicly released, but obtained by Steven Aftergood and posted this week on his Secrecy News Web site—is one of grim caution.

Counterinsurgency involves rebuilding a society, keeping the population safe, boosting the local government's legitimacy, training a national army, and fighting off insurgents who are trying to topple the government—all at the same time.

As the manual puts it, "The insurgent succeeds by sowing chaos and disorder anywhere; the government fails unless it maintains order everywhere."

From first page to last, the authors stress that these kinds of wars are "protracted by nature." They require "firm political will and extreme patience," "considerable expenditure of time and resources," and a very large deployment of troops ready to greet "hand shakes or hand grenades" without mistaking one for the other.

"Successful … operations require Soldiers and Marines at every echelon to possess the following," the authors write. (Emphasis added.) They then list a daunting set of traits: "A clear, nuanced, and empathetic appreciation of the essential nature of the conflict. … An understanding of the motivation, strengths, and weaknesses of the insurgent," as well as rudimentary knowledge of the local culture, behavioral norms, and leadership structures. In addition, there must be "adaptive, self-aware, and intelligent leaders."

Meanwhile, a single high-profile infraction can undo 100 successes. "Lose moral legitimacy, lose the war," the authors warn, pointedly noting that the French lost Algeria in part because their commanders condoned torture.