Before Tuesday’s book launch at the Bunch of Grapes, the audience was issued an unusual instruction for such an event. They were asked not to seek to get their copies of the book The Coldest Winter, signed by the man launching it, Ward Just.

The reason was obvious, but sad. Mr. Just did not write the book. His good friend David Halberstam did, but he died in a car accident in April this year.

And so, like various others of Mr. Halberstam’s literary friends around the country, Mr. Just stepped in to do the honors at an event which was as much a valedictory for a great writer as it was a discussion of the work at hand, about America’s prosecution of the Korean War.

Mr. Just read from the book, of course, but he spoke mostly about Mr. Halberstam’s devotion to his craft.

“He went to Harvard,” said Mr. Just, “where he majored not in economics or history or English literature or chemistry but in the Harvard Crimson. He spent all of his time at the student newspaper, with great success.

“Normally when you do that, your next step is to The New York Times or to the Herald Tribune or Time or Newsweek or the Washington Post, where you can begin at a lofty level.

“But David didn’t want to do that.”

Instead, in 1955 he got himself a job on a small newspaper in West Point. Miss., (the Daily Times Leader) so he could be closer to the story that interested him at that time, the nascent civil rights movement.

“He thought if you were going to look at that, the best place to look at it was from the south,” Mr. Just said.

“And the other thing he found while he was there is that journalism at its heart is a trade . . . and the place to learn that, the trade aspect of journalism, is not on The New York Times or Time or Newsweek.”

It was on small newspapers, there and later at the Tennessean in Nashville, where Mr. Halberstam learned his “great respect for fact, the trail of facts that leads to the truth or looking through the window of the truth.”

In due course he moved on to The New York Times Washington bureau, for about a year, before being sent to Viet Nam.

His tour there lasted only nine months, Mr. Just said, but “no one ever had a greater impact in that short a time, on both the story he was writing and the way reporters came to look on war and the coverage of war, as David Halberstam.”

Mr. Just called it a revolution in reportage compared with previous wars, such as World War II, where reporters were essentially — and understandably — cheerleaders for the war effort and happily subject to censorship.

But there was no effective censorship in Viet Nam. Mr. Halberstam’s accounts of the realities of Viet Nam won him the Pulitzer Prize. His first book on the subject was called The Making of a Quagmire.

His next book, The Best and the Brightest, chronicled the foreign policy decisions of the Kennedy administration and sought to explain how some of the smartest and most accomplished people in the nation took America into what Mr. Just called the abyss of that war.

In this most recent book, Mr. Halberstam had singled out an under-reported subject, Mr. Just said.

“In the library there would be a hundred books about Viet Nam and maybe one, maybe two books about Korea. He realized this was a great subject no one had really tackled, because . . . it was a war that ended in a tie, essentially,” he said.

And yet the number of combat deaths was almost identical to Viet Nam. In choosing to do the book, Mr. Halberstam had shown his talent for doing “that story that was lying right before your eyes, that nobody has done.”

Mr. Just remembered his friend not only as a great writer but as an imposing presence.

“Halberstam was about six-foot, three-inches, in great shape, with a voice that came out of his ankles somewhere. He made me sound like Liberace, [with his] big booming basso,” he said.

He could also be an intimidating interviewer, but it was his thoroughness that yielded the cream in his books.

“Rather than interview six guys, he would interview 20 guys,” Mr. Just said. “I’ve never known a man who worked any harder than he did.”

As for their personal relationship, Mr. Just said it was mostly carried on by telephone, between Nantucket or New York, where Mr. Halberstam spent much of his time, and the Vineyard.

“I spoke to him a couple of days before he died.

“He was wonderful at keeping up with his friends. He’d get so enthusiastic, so wrapped up in these books of his, that he’d say ‘Listen, there’s a wonderful novel for you in this book.’

“In this one, he had three novels for me.”

Mr. Just read from a section very early in the book, when the American Army, “not at full strength, not especially well equipped, not especially well led, but flushed with victory,” pushed too deep, too fast, into North Korea and met with disaster.

The language, the research, the detail were riveting. And sobering too. Not just because it dealt with yet another example of military hubris and tragedy, not just because David Halberstam is dead, but because it made you wonder when the lessons his books sought to teach about the conduct of war would be learned.