One war, coming up. Wolff’s second book of memories, In Pharaoh’s Army (221 pages. Knopf. $23), finds him packing off for Vietnam, while his brother is at Cambridge on a Fulbright, his father is in jail for passing bad checks and his girlfriend, the unhinged Vera, is in hysterics (““She hadn’t moved in with me yet; that opera had yet to open’’). The memoir, which has already been nominated for a National Book Award, isn’t nearly as compelling as ““This Boy’s Life,’’ though it has its share of priceless characters and set pieces. For a while, it doesn’t matter: Wolff writes such spare, whistling prose that you’d follow him anywhere, even into battle.

Wolff volunteered for duty because he imagined the military would make him a better writer and a better man – not because he was heeding a call. (In his first novel, ““The Barracks Thief,’’ the main character goes to join the Marines but their recruiting office is closed so he joins the army instead.) By the time Wolff describes paratroop training, his youthful resolve is already wilting. There’s the adrenaline rush that precedes the jump: ““To psych ourselves for the plunge we sang “My Girl’ in falsetto and danced the Stroll, swinging our shoulders and hips, flapping our wrists feyly as we made our way . . . to the open door of the plane.’’ But then there’s the jump: ““The ground, abstractly picturesque from on high, got hard-looking and particular. There were trees, boulders, power lines. It seemed personal, even vengeful, the way these things rushed up at you.''

Wolff is promoted to first lieutenant, but he’s a lousy officer – frightened, humane, out of his depth. During one training mission, he misjudges the drop zone by miles, his men end up parachuting into a smoldering garbage dump and no one speaks to him for the rest of the day. That’s the story of his life – his military life, at least. To his credit, Wolff doesn’t turn the war into a morality play about the loss of innocence, the slaughter of innocents, the horror, the horror and so on. He doesn’t do Vietnam in Sensurround. But, while it’s plain Wolff doesn’t want to push the usual buttons, it’s not always clear what buttons he does want to push.

In its more listless moments, ““Pharaoh’s Army’’ seems a ramshackle collection of memories not overly concerned with telling a larger story. There’s the time Wolff rescued a puppy about to be eaten by Vietnamese soldiers, the time he traded a rifle for a TV so he and a buddy could watch ““Bonanza.’’ All the stories are ruefully funny. Still, the sensitive soldier is a pale replacement for the cocksure kid from ““This Boy’s Life.’’ Wolff had more of an enemy in his wicked stepfather than he ever had in the Viet Cong.