THERE is an important anniversary coming up July 8, but it is not likely to get much national attention. The Buis family of Pender, Nebraska, will observe it, though, for on that day 25 years ago--July 8, 1959--their son Dale was killed in Vietnam. The Vietnam Memorial honors him as the first American to be slain in that war. The last fell 16 years later, April 30, 1975, when the helicopters evacuated the American remnant from Saigon. The 10th anniversary of that date next year will be a media extravaganza. It will mark a day that will live in ambiguity.

President Reagan has called the Vietnam War "a noble cause," and some of the veterans Myra MacPherson interviewed for this comprehensive report on "Vietnam and the Haunted Generation" agree with him. Others--most--do not. Tom Hagel typifies their attitude. A soldier who won the Bronze Star and three Purple Hearts, Tom nevertheless ended a note sent from Vietnam to his younger brother with this P.S.: "You don't have to go into the Army to win my respect. To the day I die, I will be ashamed that I fought in this war." In looking back on the Vietnam War, most Americans, I suspect, fall somewhere between these extremes of opinion. They regard the veterans as noble, but remain deeply uncertain of the cause for which they gave so much and their dead comrades everything.

In preparing this book Myra MacPherson talked to over 500 people--veterans, scholars, doctors, mental health professionals, and so she speaks with authority when she gives it as her view that the Vietnam War was "the third most pivotal experience in this century--following the Depression and World War II." Still, I wonder. The Depression realigned the political parties and brought the welfare state; World War II destroyed the malignancy of fascism, began the superpower confrontation between the United States and the Soviet Union, and unloosed that dread incubus, the atom bomb. It is hard to trace such clearcut political, economic, or apocalyptic consequences to the war in Vietnam. Ten years ago, one might have predicted that our failure in Vietnam would write finis to U.S. military interventions in the Third World. That has not proved to be the case. President Reagan has shown a willingness to use force in the most dubious battles in the Third World, and the Congress has usually supported him. When the president declares that "America is back," he means back to what it was before Vietnam--strong, confident, ready to bear any burden, fight any foe to insure the survival of liberty. If Mr. Reagan is reelected in November, it will mean, among many othe things, that Vietnam was not a pivotal experience, on the scale of the Depression and World War II, but a tragic aberration, which throws no light on how we should act in the world. Lucky the nation that can so easily escape its past.

For the 3.9 million Americans who served in Vietnam (the figure reached in a 1980 study) there is no escaping the past. It haunts them still. They bear what the author Philip Caputo, a Vietnam veteran, calls "a triple burden of guilt." In his book A Rumor of War, from which MacPherson quotes, he wrote:

"There is the guilt all soldiers feel for having broken the taboo against killing, a guilt as old as war itself. Add to this the soldier's sense of shame for having fought in actions that resulted, indirectly or directly, in the deaths of civilians. Then pile on top of that an attitude of social opprobrium, an attitude that made the fighting men feel personally morally responsible for the war, and you get your proverbial walking time bomb."

Myra MacPherson is at pains to confront that stereotype, the veteran as walking time bomb, with the reality of men getting married, raising children, and making their careers. She never minimizes, however, the immensity of guilt with which even the most successful Vietnam veterans have had to struggle. It takes a "World of Pain," Keats says in his letters, to turn an "Intelligence into a Soul." From listening to the moral anguish contained in the voices of the men in this book, it is clear that they are Souls, made that way by what one of them calls a "hellified place."

Not so the voices of the men who did not go to Vietnam; Myra MacPherson has a whole section on them, the men who out of principle and fear evaded the draft, and, with notable exceptions, they sound lighter, lesser --more like Intelligences than Souls. She puts the scandal of the draft in one splendid sentence: "Above all, Vietnam was a war that asked everything of a few and nothing of most in America." It asked nothing, for example, of the sons of the senators and congressmen who year after year, voted the money to prosecute the war. One study, done in 1970, found that 234 sons of legislators came of age during the prime years of the war, but only 28 of that number went to Vietnam; only 19 "saw combat"; and only one, the son of Maryland Congressman Clarence Long, was wounded.

Senator Barry Goldwater (R--Ariz.), the hawk, had two sons who flunked the physical as did Senator Alan Cranston (D --Calif.), the dove. On the other hand, let it be recorded here that the son of Tennessee Senator Albert Gore--Albert Gore, Jr., who is himself now a Democratic congressman from that state--"felt an obligation to go to the war he detested so that his father's (anti-war) position would not be compromised."

Meanwhile, back at the Harvard Divinity School, Mr. Reagan's budget director, David Stockman, was sitting out the war. "Once I went to divinity school," he told MacPherson, "I never worried about the draft that much." The gods of irony must have been off duty in 1981 when Stockman sought to cut government funding for the Vet Centers, the community-based counseling centers for Vietnam veterans. He said they were "a dispensable expenditure." Some of the veterans MacPherson talked to feel the same way about him.

"The climate in the sixties," says MacPherson, "made draft dodging not just acceptable. . . . Beating the draft was a status symbol." Up until 1968 you could be deferred by going to graduate school and studying, say, the novels of Virginia Woolf. "If time ran out, you could teach school, another deferment. . . . From 1963-1966, you were deferred if married. During those years there was an immediate 10 percent rise in marriage rates for twenty and twenty-one-year- olds." If all else failed and you received a draft notice, you could still avoid service by emulating a man MacPherson interviewed who cut off his finger. Alternatively, you could starve yourself, make your blood pressure rise by various tricks, or kiss the examining sergeant. One San Francisco draft counselor recalls that "all of my clients who faked (homosexuality) got their exemptions--but they drafted the one fellow who really was gay." Trust the Army to do that!

However, you could not adopt any of these strategems if you were someone like Tom Hagel and lived in a place like the sand hills of Nebraska, "a land of super patriots." Asked about the dodge of getting a psychiatrist to write an exempting letter to the draft board, Hagel says, "That kind of maneuver illustrates the class difference. In my environment that would never have crossed anyone's mind. In my town we didn't even have a psychiatrist." Nor did they have pyschiatrists in the urban neighborhoods that were home to the 350,000 young men inducted under "Project 100,000." Launched in 1966, this Great Society program was targeted at what then Secretary of Defense Robert McNamara called "the subterreanean poor." Standards were lowered to admit these young men; 41 percent were black, and a "disproportionate number" saw combat in Vietnam. With such an abundant supply of cannon fodder to choose from, Lyndon Johnson did not have to call up the Reserves or otherwise spread the pain of sacrifice to the politically temperamental middle class. Thus in 1965-66, college graduates made up only 2 percent of all draftees. Thus out of the 1,200 graduates of Harvard's class of 1970, 56 went into the military, and only 2 went to Vietnam. Just five miles away from Harvard, in the working class neighborhood of South Boston, it was a different story. Southie lost 25 dead in Vietnam, 15 of them marines. According to a former Marine officer, the novelist James Webb, "If every community had the same ratio of men killed, there would be 250,000 dead marines." We prefer to think of America as a classless society, but it is hard to square that belief with facts like these. Vietnam may not have been a rich man's fight-- Marxist efforts to connect it with "late capitalism" are patently absurd--but it was a poor man's war.

To be sure, some of the poor draftees got something positive out of the experience, as Herbert Denton, a black reporter for this newspaper and Vietnam veteran, reminds us: "I hate to sound Pollyannish but the guys I was drafted with, the military settled them down. It settled me down in a similiar way. These are 'no fixed address' guys and the military gave them something. When we graduated from basic, one said to me, 'I've never graduated from anything before in my life.' They are now truck drivers, bus drivers, cops. One's a liquor distributor. The sense of mortality and two years of confinement settled them down." Perhaps the war also helped settle down the over 300,000 men who were wounded in it, and the 6,655 who lost limbs in it. But at what a price? Incidentally, a grateful nation pays $1,661 per month to the men who lost both legs above the knees, but only $311 to those, like "Eddie" of South Boston, who lost only one leg. Eddie wittily complains that he has to keep going back to the VA for "reevaluation--to see if my leg is still worth 60 percent disability. I keep telling 'em, 'It ain't gonna grow.'"

Myra Macpherson talked to hawks and doves, to gold star mothers and deserters, to the women who served in Vietnam and to men like "Kenny," fairly staggering under the triple burden of guilt described by Philip Caputo, "Hey, lady," he told MacPherson, "look me in the eye. I was taught to kill and I loved it. . . . I enjoyed cuttin' the slopes' heads off." He says he realizes "a lot of it was senseless. . . . It was murder." "How do you make it through the days," MacPherson asked him. "I rely heavily on drugs. Pot. Quaaludes. Seconals, amphetamines. I never heard of marijuana till I went to Vietnam. Hell, I'd never heard of Vietnam till I went to Vietnam."

Kenny is part of the legacy of Vietnam; the war goes on for him. It goes on for little Kerrie Ryan, too. She is a pretty girl born with a hole in her heart, double reproductive organs, missing bones, twisted limbs, and no rectum. Her father believes that his exposure to Agent Orange is responsible for her condition. "'This," says one veteran, "is the first war that reached into our maternity wards."

Long Time Passing is not without faults. Myra MacPherson's narrative course is unnecessarily repetitious, her prose occasionally rushed, her anger at those who hold President Reagan's view of the war obtrusively insistent. She stumbles over the odd fact: Ronald Reagan did not make Hellcats of the Navy during World War II, but in 1957; the author of Casualties of War is not Donald Lang, but the late Daniel Lang. Still, she gets everything that matters right, and her book's achievements far outweigh its flaws. In Long Time Passing she does justice to an extraordinary range of experience and emotion. Rage, shame, battle lust, a dark rainbow of guilt and regret and grief--these are just a few of the feelings that Myra MacPherson elicits from the veterans with the kind of skillful empathetic questioning a master psychologist might envy. There have been many books on the Vietnam War, but few have captured its second life as memory better than Long Time Passing.