BOOK REVIEW / FAMILY MEMOIR : A Reporter’s Journey to the Core of His Heritage : RECONCILIATION ROAD: A Family Odyssey of War and Honor <i> by John Douglas Marshall</i> , Syracuse: Syracuse University Press $24.95, 312 pages

At a quiet moment during a dinner party the other night, a man I didn’t know said, with no apparent lead-in, “You know, every male of our generation was profoundly affected by Vietnam. Our individual reactions--to go or not, to deal with our decision--influenced everything that followed in our lives. I try to explain it to my kids, the ongoing centrality of that time to me, and they act as though I’m speaking a different language.”

John Douglas Marshall, a feature writer for the Seattle Post-Intelligencer, would certainly understand what the speaker was talking about. The oldest son of a prominent army family, the grandson of war historian S.L.A. “Slam” Marshall, he had been long groomed for active military duty.

After enlistment, however, he realized that at heart he was a pacifist and ultimately applied for, and was granted, status as a conscientious objector. He thus became one of the 7,493 men already conscripted who were granted c.o. discharges during the Vietnam conflict (172,000 others were never drafted).

To the Marshall family, especially to his grandfather, John immediately became a pariah, a persona non grata --a situation seemingly made permanent by Slam Marshall’s eventual death. As a result, John was a virtual orphan during much of his 20s, marrying, beginning a career, finding his way into maturity alone.

He never doubted or regretted his ethical choice, but naturally he felt sorrow, some anger, loneliness.

And then, years later, a scathing article in American Heritage magazine cast aspersions on some of Slam Marshall’s most controversial historical research--the book “Men Against Fire,” in which he had asserted that many soldiers in combat never so much as fired their guns at the enemy.

This startling conclusion was said to be based upon extensive post-battle interviews--conversations that some now accused had never taken place.

Surviving members of the family--John’s father and brother among them--were outraged at these charges and asked John, now a respected journalist, to use his investigative skills to vindicate Slam’s reputation, to prove his detractors false.

Thus began John Marshall’s personal odyssey, a journey that encompassed more than 10,000 miles. As he traveled the country, to army bases in Texas and Kansas, to Sun Belt communities where Slam’s old buddies had retired, to archives in Washington and Pennsylvania, he tried diligently to piece together the puzzle that was not only his grandfather, but his own heritage.

Who was this short, assured general, this consultant to Mike Wallace, this prolific writer whose books influenced generations of army officers, this man who said, late in life, that the greatest compliment he ever received was that he had never been afraid of anything?

What made him so intransigent in his opinions, so stubborn in his refusal to allow for a different point of view? Was it his diminutive size? His ego? A fierceness that discouraged the dissent of friends or colleagues?

John Marshall documents his progress with a reporter’s eye and ear. His prose is clear, factual, even-handed--and that is, perhaps, this interesting book’s only flaw. Describing his experience, he writes, “These days of end game on the road have taken on the quality of a speeded-up movie, hit-and-run visits with people, long stretches doing 75 on the Interstate.”

In the rush, in the deeply felt obligation to tell all, the narrative sometimes blurs, and in the end, few individual characters stand out in a reader’s memory. Rather, we are left with an impression of an honest, earnest man chipping away at an enigma that remains forever aloof. Clearly John Marshall is an individual of passionate conviction. Of his life-altering resolve to become a conscientious objector, he notes, “I have always felt . . . that if I never did anything else worthwhile in my life, at least I did this. I took a stand for what I believe.”

When, late in the book, someone remarks that Slam Marshall shared this courage to act on belief, John finds peace of a sort in the idea that he does, therefore, participate in a family legacy, that he does, after all, belong.

But we who have followed him on his quest of attempted discovery are left with a slightly different impression. For all of his bravado and bluster, for all of his erudite writing and long-term theoretical impact, Slam Marshall emerges as a cold and selfish autocrat.

His grandson, by bravely refusing to fit himself into another’s mold, has escaped this patrimony and become instead that most admirable of successes: a decent human being.