When American politicians who favor the retreat from Iraq speak against President Bush’s policy, they often describe American soldiers policing a civil war. The implication, of course, is that there is no real difference between the sides fighting. It is Sunnis versus Shiites, an intra-Islamic feud.

Michael Yon’s new book, “Moment of Truth in Iraq” (Richard Vigilante Books, 256 pages, $29.95), gives the lie to this easy euphemism. The author describes in detail the medieval cruelty practiced by Al Qaeda’s minions in Iraq, and how American and Iraqi efforts to oust them from their seats in Anbar and Diyala in the last year were nothing less than a second liberation. The war is now between Iraqis who seek a peaceful and prosperous future, and forces that seek the perpetual bondage of Iraqis. In this struggle, America is on the side of the angels.

For those of us who read Mr. Yon’s Web log regularly, this depiction will come as no surprise. But for many Americans whose news is filtered through a class of experts that consistently got the rebellion in Anbar wrong — saying we merely rented sheiks to turn on the enemy, or that the Anbar operations were propaganda — Mr. Yon’s account will be a necessary corrective.

One of the major problems for the war prior to 2007 was that the chaos, death, and refugees caused by Al Qaeda’s cruelty were blamed on the Americans, because Al Qaeda came to Iraq after the fall of Saddam Hussein. “The correlation of media, counterinsurgency, cult and leadership seemed painfully obvious to me,” Mr. Yon writes. “Al Qaeda was a cult that had skillfully used our mistakes to make itself great among the people, while placing on us the ignominy of its own brutality.”

Mr. Yon, a former Green Beret, got the story of the war for Iraq by embedding with the Americans fighting it. Unlike many of us who have also embedded with military units, Mr. Yon tagged along in the midst of battle. Very few reporters actually do that. (One other example is Dexter Filkins of the New York Times, who accompanied soldiers in 2004 as they tried to take back Fallujah.) Most of the reporting that you read from the front is based on interviews with soldiers after the fact.

In telling his story, Mr. Yon brings a rare combination of skills. To start, he understands war and weaponry. He knows how to hear the difference between Kalashnikov and M-16 fire. But he is also a clear writer. Mr. Yon draws his subjects in sharp detail and writes at his best moments in short blasts that capture a battle’s rhythm.

This book is different from many other Iraq books in that Mr. Yon makes no pretense of being unbiased. He sees his job as telling the story of soldiers and correcting the failures of the military in getting their side of the story out to the world. He is not neutral; he is rooting against Al Qaeda. At times he even calls them “animals.”

But Mr. Yon does not shy away from writing about the war’s failures as well as its successes. He says, for example, that at the end of 2006, the war for Iraq was nearly lost. He doesn’t over-egg the pudding and declare victory prematurely; he writes that victory is now possible, but not yet achieved. Mr. Yon admits that a lot of reconstruction money will go to lining the pockets of corrupt officials, but warns that this kind of approach is a small price to pay for the peace it will keep.

In one of the book’s best chapters, the author details the arrest of an Iraqi police chief, known as General Hamid, in the city of Hit. The Iraqi had been a hero in fighting Al Qaeda, but after vanquishing the enemy he had become too corrupt. He was said to be releasing detainees for ransom money, a sure sign that any peace purchased in the counterinsurgency could evaporate as the population learned not to trust those people who were supposed to protect them.

The chapter ends in a dramatic showdown between American Lieutenant Colonel Doug Crissman and General Hamid’s police force. They face off outside the police station, armed Americans and armed Iraqis. The commanding American officer then asks Mr. Yon to take a picture of him with General Hamid. “Acting solely on his own and with no direct orders from above, but seeing that a bloodbath was about to happen, Crissman had pulled a plan from the sky,” Mr. Yon writes.

While Crissman had continued discussing seemingly important issues with General Hamid, soldiers from Task Force 2-7 Infantry had been outside, quietly separating Iraqi police, disarming, and flex-cuffing them. No shots were fired. No punches were thrown. Crissman managed to arrest an entire police station by using a photo-op to distract a proud, and some might say vain, general just long enough to disarm him.

That’s not exactly a glowing portrait of our new Sunni allies, but it’s a very real one. Like the rest of this wonderful book, this small anecdote captures the complexities of a new war that the author argues convincingly is still worth fighting.

elake@nysun.com