One day last April, Gay Talese was a guest at an analytical writing class I was teaching at the University of Southern California. Introducing my old friend from The New York Times, I said that he and Tom Wolfe and David Halberstam were the greatest reporters of their generation.

“That’s sweet of you to say,” said Mr. Talese, whose elegant writing in The Times and Esquire changed the way other reporters, including Mr. Wolfe, thought about their craft. “But David was the best reporter.”

So he was. I should have said that they were the three most influential craftsmen of that generation. As a reporter, Halberstam was the best of them, far more important, though he couldn’t write nearly as well as Mr. Talese or Mr. Wolfe. His subjects, particularly civil rights and Vietnam, were heavier, of greater consequence—although, God knows, he could be ponderous on the printed page.

Less than a week after Mr. Talese talked of his friend—his best friend—David was dead, killed in a tragic accident near San Francisco.

I’m sure there are many who think newspapers and television newspeople make too much of their own, but not this time. Halberstam’s work and life are symbolic of a golden age of reporting, a time when journalism was much more than just another entertainment, a time when energetic young men and women made a difference, made this a better country.

Halberstam led the way, literally. There was something of Paul Revere and Thomas Paine in his journey from Harvard to becoming the only reporter on the smallest newspaper in Mississippi—because he thought race and civil rights was the biggest (and untold) story in the country. Others came after him with typewriters and cameras and their hearts in their throats to make Americans confront this stain on the flag.

Then he went to Vietnam, not because he was antiwar—his father was a U.S. Army doctor. More than anyone else, Halberstam made Americans confront the reality of what our government was doing there. Others, younger men, particularly Bob Woodward and Carl Bernstein, followed his lead, showing that the highest officials of the U.S. government were essentially mounting a coup against country and Constitution.

Is that mythology? Yes. But it’s not a myth. Halberstam, not an easy man to ignore, was at the center of it. His 1972 book The Best and the Brightest has become an American classic not because it eviscerated the American government but because it was so American, so idealistic in its belief that America was better than what America was doing.

Then a couple of years ago, he began telling anyone who would listen that his upcoming book on the Korean War would be his best. It’s not—The Best and the Brightest still is—but it is an important book, compelling in David’s wordy, authoritative way.

And, though the battle scenes and analysis are strikingly vivid—that’s why it’s compelling—The Coldest Winter: America and the Korean War isn’t really about Korea.

In his introduction, he writes of going into the public library in Key West, Fla., and seeing that there were 88 books on the war in Vietnam but only four on the Korean War. He notes, “To the degree that the Korean war ever had a niche in popular culture, it was through the Robert Altman antiwar movie (and then sitcom) M*A*S*H, about a mobile surgical hospital operating during that war. Ostensibly about Korea, the film was really about Vietnam, and came out in 1970, at the highwater mark of popular protest against that war.”

And The Coldest Winter is really about Iraq and Vietnam.

I was home from school, sick I guess, on June 30, 1950, when a black-and-white map of the Korean peninsula appeared on our little Philco television screen. The communists in North Korea had invaded the good guys of South Korea. Soon enough a voice from somewhere mentioned things like the 38th parallel—and said that United States troops would soon be there to teach the Reds a lesson they would never forget.

“Yes!” I thought or maybe shouted. Finally! It seems I was not alone. President Harry S. Truman was saying, “By God, I’m going to let them have it!” The commander of United States forces in the Pacific, the immortal Douglas MacArthur, came to see it as a chance to destroy Red China.

Of course, there was a difference: I was a 12-year-old boy who thought America was invincible.

Or was there much difference? In this telling, the president and the egomaniacal general come across as being as ignorant as I was regarding the mind and strength of the enemy. It’s the same old (or is it new?) story of a diminished military, lousy intelligence and worse arrogance. Halberstam tells this sad tale powerfully, though intermittently soars off into flights of sometimes unnecessary biography and analysis. He never uses one word when 13 will do. He writes that Americans were “surprised” at how poorly our troops fought at the beginning, then adds, “it was more than a surprise; it was nothing less than shock.”

So be it. The more important impact of the book involves the way the military works. If The Best and the Brightest was about the hubris and lying of Washington, The Coldest Winter is about the hidden hubris of generals and colonels, beginning with the mad genius and willful stupidity of MacArthur—a man feared by everyone above him, even President Truman and Secretary of State Dean Acheson.

Much of the book in fact revolves around the weakness of political figures afraid to take on the self-promoting national monument that MacArthur became. Few people my age will ever forget being called into school auditoriums in 1952 after Truman finally dismissed MacArthur for obvious insubordination. We were seated there not to hear the president, but to hear MacArthur’s “old soldiers never die” farewell speech to his right-wing idolaters in Congress.

There’s wonderful reporting in this book. As always Halberstam roamed the countryside, interviewing at length (and again and again) the old men who had been in Korea almost 60 years ago. He got their stories, and they tell us what it was like in that place at that time.

What will stick with me, and I hope with many Americans, is from Col. Paul Freeman, West Point ’33, commander of the 325th Regiment, Second Division, United States Army, writing home to his wife, Mary Anne, on September 12, 1950:

“It’s poured for the last three days. … Our artillery planes can’t go up and we are blind. We’re just sitting here, taking it. We’ve already repulsed thirteen attacks in force—ten of them at night. The nights are the worst. The gooks pour in all over, and we continue to slaughter them. The rest of the time we’re continually under fire. … Our losses are terrific. I have left less than 40 percent of what I had on the 31st of August when this particular battle started. Almost all of my company officers have been lost. We are bitter about the whole thing. We fight desperately for all we’re worth; not only because our course is right, but also because we’re fighting for our survival. But it all seems so useless and stupid. To ‘liberate’ South Korea, we’re destroying it and its people. All Koreans hate us. Everyone here is an enemy. We can’t trust anyone. … I feel more and more that we have made a supreme error in committing our forces to this bottomless pit.”

Richard Reeves, author of 14 books and senior lecturer at the Annenberg School for Communication at the University of Southern California, was a colleague of David Halberstam at The Times.