Elliot Ackerman is the author of “Dark at the Crossing,” a finalist for the 2017 National Book Award. His latest novel, “Waiting for Eden,” will be published this month.

The Global War on Terrorism War Memorial Act that Congress passed last year calls for a new monument on the Mall. Like the Vietnam Veterans Memorial, it will be designed by the winner of a national competition. Unlike the Vietnam project — or any other war memorial on the Mall — it must solve this riddle: How does one memorialize a war still being fought? The question extends beyond architecture. C.J. Chivers, a Pulitzer Prize-winning correspondent for the New York Times, has taken it up in his second book, “The Fighters: Americans in Combat in Afghanistan and Iraq.”

(Simon & Schuster)

When erecting a war memorial, in stone or in words, it can be difficult to say anything new: the lives cut short, the misguided strategies of politicians, the societal journey from idealism to disillusionment. We’ve heard it all before, haven’t we? After nearly 20 years, our wars in Iraq and Afghanistan have exhausted our collective attention spans. I’m a veteran of both conflicts, and I admit that they have come to exhaust my attention span, too. I was hesitant to pick up “The Fighters.” What a mistake that would have been. This book is remarkable.

Authors like Steve Coll (“Ghost Wars,” “Directorate S”) and Tom Ricks (“Fiasco,” “The Gamble”) have written sweeping and definitive accounts of the so-called global war on terror. “The Fighters” belongs alongside those volumes, but it achieves its own broad scope by relying on the more intimate canvas of individual experience. Chivers writes in the prologue, “This human experience of combat is often unexpressed by the public relations specialists and senior officers who try to explain the purposes of operations rather than describe the experience of them.”

Chivers, then, chooses to follow six primary characters from the Army, Navy and Marines through multiple deployments. Their stories are told in fragments across four themed sections: “Storm,” “Bad Hand,” “Counterinsurgency” and “Reckoning.” This division loosely follows the arc of both wars and is kept intentionally simple. It’s as if Chivers doesn’t want to burden or distract the reader with an overly byzantine rendering of his subject. The complexity he seeks is a moral one.

One of the most compelling stories in “The Fighters” is that of Chief Warrant Officer Michael Slebodnik of the Air Cavalry, pilot of a Kiowa Warrior helicopter who flew missions in both Iraq and Afghanistan. In one particularly vivid passage, he and his co-pilot, Mariko Kraft, catch three insurgents setting up a rocket in broad daylight. They gun two of them down, with the third managing to escape. That night, Slebodnik finds Kraft: “ ‘I feel bad for their families,’ she told Slebodnik. “. . . ‘They did not just sacrifice themselves. They sacrificed their families.’ . . . Slebodnik was unmoved. . . . He sat down and wrote home, sharing with [his wife] Tanja a detailed account. ‘Today I killed a man,’ he began. For years he had trained for a moment that at last had played out in front of his Kiowa windscreen. . . . ‘My only real thoughts,’ he wrote later, ‘have been how could I have done it better to get all 3.’ ”

A singular aspect of our most recent wars is that they are the first protracted conflicts to have been fought by an all-volunteer military. Chivers doesn’t shy away from the moral complexity of volunteerism. What does it say about us that we chose to fight? Chivers gives the thrill of combat and its horror equal time. What he vividly portrays in the character sketches is a group of fighters eager to kill yet also afraid of death. His extended section on Army Spec. Robert Soto, a former theater major from New York who found himself in Afghanistan’s Korengal Valley, captures the duality of war as powerfully as anything I’ve read.

Here is the horror after Soto is caught in an ambush: “Block, he thought. Block, block, block. Shut down emotions. You can’t dwell. You can think about this now or we can get back safe and you can think about it later. Soto chose later. At eighteen, he had learned how to switch himself off.” And here is the thrill of Soto initiating an ambush a few weeks later, against more than a dozen of the same Taliban fighters who had ambushed him and his comrades: “Adrenaline rushed through Soto. His heart rate spiked. His muscles seemed coiled to pounce. . . . He entered the peculiar mind-set that can settle over a combatant in the seconds before battle, a feeling of absolute, intoxicating clarity.”

Much of the “reckoning” in the last section of Chivers’s book occurs as the fighters return from war and attempt to reconcile the thrill with the horror. A decorated veteran I know who is often invited to speak about the actions that earned him his medal equates the experience to being continually honored for the worst day of his life. Can the worst day of your life also be the best day of your life? This, obviously, isn’t a question only veterans wrestle with. It’s universal. And so is the appeal of “The Fighters.”

Although the wars in Iraq and Afghanistan haven’t ended, they have wound down. The building of a memorial on the Mall, scheduled to be completed by 2024, seems to be a point of departure, a gesture that these wars might finally begin to consign themselves to the past. Like many veterans, I am curious to see what design is selected. Whatever it is, I hope to one day take my children there. If the memorial is done well, perhaps it will convey to them a sense — no matter how ephemeral — of what it was like for those of us who fought. If it doesn’t, we’ll have books like “The Fighters,” which is a memorial in pages.

in Combat in Afghanistan and Iraq

By C.J. Chivers

Simon & Schuster.

356 pp. $28