Where the Chariots Were Engulfed : Near-misses in the Vietnam War : IN PHARAOH’S ARMY: Memories of the Lost War, <i> By Tobias Wolff (Alfred A. Knopf: $23; 221 pp.)</i>

Imagine the button; the notorious and apocryphal button--it is a set of keys, I believe--that was available through the Cold War, and since, for unleashing Armageddon. Would it be black plastic like a doorbell buzzer? Or brushed steel like the on-off in an expensive sound system? Might it squeak when pressed? Would it bear the faint sheen of mayonnaise from a sandwich lunch at the desk--the President touching it lightly while thinking large and lonely thoughts?

It is the button or its equivalent that Tobias Wolff considers in these 13 pieces from the Vietnam War. He approaches its horror somewhat as Hannah Arendt approached the horror of an Adolf Eichmann: through the banality, the small things, the casual human expedients which, hitched to a mighty killing technology and a distant and abstract purpose, caused such wreckage.

He does not deal with a My Lai massacre, as Tim O’Brien has just done in “In the Lake of the Woods,” but with the near-misses. There are civilians killed, as well as soldiers from both sides, but Wolff writes less of the bullets tearing flesh than of the long demoralization, dirt and moral carelessness that wield a high-powered weapon and corrode its safety catch.

“In Pharaoh’s Army” is one of the genuine literary works produced by a war that, perhaps without our quite noticing, has given us several: Michael Herr’s “Dispatches,” Tim O’Brien’s “Going After Cacciato” and, only two years ago, his “The Things They Carried.” “Things” came 18 years after the war ended; Wolff’s book comes 20 years after. If this seems belated or out of date, it is not. Wars can take as long to mature as the olive trees--a quarter of a century--that they destroy. “The Red Badge of Courage” came 30 years after the Civil War. It was 50 years after Napoleon’s invasion of Russia that Tolstoy wrote “War and Peace.”

Where Herr and O’Brien write with passionate immediacy, Wolff’s style is finely distilled, ironic, apparently distant. It is the difference between the romantic and the classical. But out of Wolff’s distances come an unexpected tremor, a phrase that rips like lightning, an elusive design that completes itself in sudden revelation.

The 13 sketches are drawn from Wolff’s service in Vietnam and narrated in the first person. They have a fictional finish to them, but only one--an elaborate vignette about a bloodthirsty Ivy League spook who is also an aesthete of war--seems excessively contrived. Wolff’s narrative has a crystalline transparency; his stories hold us, relinquish us to engaging side-trips, and bring us back as we begin to need to get back. They draw a picture and undermine it just enough to set up tension without destroying it. At the end, a sequence or a phrase will frequently appear that make it evident how much more we were seeing than we were aware of.

Wolff got away from a torturous childhood--he wrote magnificently in “This Boy’s Life” of his mother and his estranged con-man father--by joining the army. It would make him, perhaps, a “man of honor” and provide nutrients for budding as a writer.

He gung-ho’d his way through basic training, parachute school and the Special Forces program. The warrior self-image died there--”I simply ceased to inhabit my pose”--but he went on to officer candidate school, graduating 49th out of the 49 who didn’t wash out. One reason he was retained, he suspects, was because he was in charge of writing the traditional graduation skit. “They kept me on to produce a farce,” he writes. “That is how I became an officer in the U.S. Army.” Wolff can do the easy line; he is enough of an artist not to disdain it, because we will need it for the harder lines to come.

In Vietnam, having studied Vietnamese, he was seconded from the Special Forces to act as liaison with a South Vietnamese artillery battalion in the Delta, instead of going north where the heavy fighting took place. The assignment provided him with his vision: the war not as dramatic destruction but as a terrible erosion.

Except for the Tet offensive--of which he gives a wonderfully effective account--there was little frontal confrontation. The Americans had to contend with snipers, ambushes and mines; with a hidden enemy whose depredations were too frequent to allow anything but constant tension, and too sporadic to keep them at any kind of fighting pitch. Visiting the big U.S. base at Dong Tam, he finds mud, dilapidation, purposelessness and the pervading stench of badly kept latrines.

“At Dong Tam I saw something that wasn’t allowed for in the national myth--our capacity for collective despair. People here seemed in the grip of unshakable petulance. It was in the slump of their shoulders and the plodding way they moved. A sourness had settled over the base, spoiling and coarsening the men. The resolute imperial will was all played out here at empire’s fringe, lost in rancor and mud. Here were pharaoh’s chariots engulfed; his horsemen confused; and all his magnificence dismayed.”

This comes in the book’s first chapter, but there is much more at work. Wolff and Sgt. Benet, a seasoned black veteran of Korea, are stationed with their Vietnamese battalion, miles away. They lack the base’s security and its PX comforts. They visit it to scrounge; what they have to offer by way of trade are Viet Cong trophies: battle-flags, belt-buckles, Chinese rifles. They get them from the Vietnamese troops and provide them with PX cognac, cigarettes and watches. Whether the trophies are authentic is another matter; however, Wolff reasons, they are manufactured by the same artisans who furnish them to the Viet Cong. It is a question, if you will, of bypassing the middleman.

So much for squalor and irony. But there is more. Before we get to Dong Tam we see Wolff and Benet barreling along a jungle road, the floor of their vehicle padded with sandbags as illusory protection against mines. They come to a knot of Vietnamese standing in the road; conceivably it could be an ambush, and they don’t slow down. At the last moment the Vietnamese jump out of the way, but their bicycles are crushed. A little slower and they would have been crushed.

A massacre, a tiny My Lai if you like, that didn’t happen but could have. Somehow, because there was no actual horror, we see more clearly what underlay the horror. And finally, to hammer in the theme of banality: The reason that Wolff and Benet were speeding down the road was to trade for a color TV at Dong Tam. It is Thanksgiving and they wanted to watch the “Bonanza” special on something better than their black-and-white set.

Irony often; the tailings from an iron story. It is wrought-iron, bent with a skill and sometimes a beauty that allows it to reflect light, as well as bear weight. Many passages that begin with a sardonic chill end in ghostly compassion. A fellow officer buys seven suits plus sports coats from a Hong Kong tailor. His sartorial future is set, except that he is killed. Wolff tries to imagine friends or relatives in America wearing the suits, “but what I see instead is a dark closet with all his clothes hanging in a row. Someone opens the closet door, looks at them for a time, and closes the door again.”