Michael Kelly, the Atlantic Monthly's editor-at-large and a Washington Post columnist who abandoned the safety of editorial offices to cover the war in Iraq, was killed Thursday night in a Humvee accident with the Army's 3rd Infantry Division.

Kelly, 46, the first American journalist to die in the war, had also served as editor of the New Republic and National Journal and as Washington editor of the New Yorker.

But his decision to become embedded with U.S. forces marked a return to his reporting roots, since he covered the first Persian Gulf War as a freelance writer. While one Australian and two British journalists have been killed covering the 2 1/2-week-old war, Kelly's death is the first among the 600 correspondents participating in the Pentagon's embedding program.

"He didn't need to do this," said Martin Beiser, managing editor of GQ magazine, who edited Kelly during the first Gulf War. "He's just a born newsman. He wanted to be where the action was. The courage he showed in the last war put his career on a whole new trajectory and he didn't need to prove anything."

Cullen Murphy, the Atlantic's managing editor, said that "Mike had more than just a journalistic side. He did have a dog in this fight. He believed a proper effort was underway here and he wanted to chronicle it. He saw journalism not just as a craft or a game, but that he was accomplishing something."

In a March 17 appearance on ABC's "Nightline," Kelly, who dodged Iraqi gunfire during the 1991 war, spoke about the risks of this assignment:

"My own gut feeling is that there's some degree of danger, but if I was going to, sort of, rank danger in things that reporters do, . . . it would be . . . a lot more dangerous to be wandering around Chechnya than doing this, or wandering around Sierra Leone. I mean, here there is some element of danger, but you're surrounded by an army, literally, who is going to try very hard to keep you out of danger."

A Navy spokeswoman in Kuwait, without naming Kelly, said that a soldier and a reporter were killed near Baghdad when a Humvee went into a canal in an accident. President Bush expressed his condolences, and Pentagon spokeswoman Victoria Clarke told reporters, "Mike was just a phenomenal journalist."

Kelly is credited with revitalizing the respected but sometimes dull Atlantic. The Boston-based monthly won three National Magazine Awards last year and has carried many high-profile cover stories, including a three-part series on the cleanup of the World Trade Center site. He was hired by Washington businessman David Bradley, who bought the Atlantic in 1999. Kelly stepped down as editor last fall and planned to write a book about the history of the steel industry.

The Gonzaga High School graduate moved in recent years to a beach house in Swampscott, Mass., with his wife, Madelyn, and their sons, Tom, 6, and Jack, 3. In each editing job, Kelly inspired fierce devotion among those who worked with him.

"He was gentle, incredibly funny, a little disorganized, passionate and utterly non-egocentric," said New Republic Editor Peter Beinart. "What made him a great, great editor was that he could get more excited about your story than you were. You'd walk out of that room on fire."

Murphy recalled how Kelly won over the Atlantic's staff amid skepticism that an outsider with strong political views, initially commuting to the Boston office, might shatter the magazine's venerable traditions.

"He was a very affable person, very funny about himself," Murphy said. "As a friend, he was always loyal. . . . He had this knack for mixing with an extraordinarily diverse range of people. He enjoyed going to the steam baths in Chelsea."

During his years in Washington, Kelly had little interest in appearing on television or working the Georgetown social circuit. "He was a great raconteur but not a schmoozer," said Hanna Rosin, a New Republic colleague who is now a Washington Post editorial writer. At one magazine gathering, "he spent the whole party under the stairs, talking to his wife and me." Rosin said Kelly was in "a whole different world" in Swampscott, tooling around in his red convertible, a 1966 Mustang.

Susan Ellingwood of the Committee to Protect Journalists called Kelly "a real role model," saying he brought her into journalism by hiring her as an assistant. "He was always missing his deadlines at the New Yorker, and we'd go out for martinis" before he finished his story, Ellingwood said.

As a syndicated columnist, Kelly was a caustic conservative who was merciless in his criticism of Bill Clinton and Al Gore and generally supportive of President Bush, especially on foreign policy. The Boston Globe wrote that he "turns a Mencken-like blowtorch on those he deems guilty of nincompoopery, dishonesty or both."

During the Monica Lewinsky scandal, he wrote: "Bill Clinton and his morally bankrupt defenders intend to do whatever it takes to discredit his impeachment, to savage the reputations of those who supported it and to establish Clinton as a sort of hero, the president who bravely defended the Constitution against a small band of hate-blinded fanatics." In 1997, New Republic owner Martin Peretz, a close friend of Gore, fired Kelly as the magazine's editor over his continuing attacks on the Clinton administration. His departure was cheered at the Clinton White House. Peretz later called him a right-wing "wacko."

Kelly resisted such characterizations. "It made him angry," Beiser said. "He once said to me, 'I'm mean to everybody.' " Beinart said Kelly was far more interested in the character of politicians than their ideology. He occasionally took Bush to task, writing in The Post last summer: "Bush's control of his presidency seems to be slipping more and more away. . . . The first President Bush lost his job because the American public came to think he didn't really care much about doing it. His son is starting to look a lot like a chip off the old 9-iron."

Fred Hiatt, The Post's editorial page editor, said Kelly "was fearless as a columnist. He didn't care who liked him or who didn't like him. . . . A lot of Clinton and Gore partisans thought he was over the top. He was not bashful about using his skills as a wordsmith to hammer somebody."

But, Hiatt added, "although he could certainly write diatribes, his foundation as a columnist was always as a reporter. He was interested in facts."

Margaret Talbot, a New York Times Magazine contributor who worked with Kelly at the New Republic, said that while Kelly was a "pugnacious" writer, outsiders would be surprised to learn "he was an extremely gracious, almost gallant, person. He was not the sort of editor to impose his point of view on what you were writing, even though he had strong points of view."

As for his final assignment, Talbot said: "He had gone way out on a limb in support of the war and he was going to be there to witness it."

Friends and associates stressed the contrast between Kelly's two-fisted journalistic style and his soft-spoken nature as a devoted father. "He himself would talk about the good Michael and the bad Michael," Hiatt said. In 1998, after Kelly had become editor of National Journal, one of the New Republic writers he nurtured, Stephen Glass, was exposed as a fabricator. Kelly apologized for his role, saying: "I take full responsibility for the flaws in judgment that allowed this to happen."

Kelly grew up on Capitol Hill, the son of Thomas Kelly, a reporter for the now-defunct Washington Daily News, and Marguerite Kelly, who writes the Family Almanac column for The Post's Style section.

"I had always wanted to be a newspaper reporter, because I admired him most in the world," Kelly told the Boston Globe about his father last year. "Still do."

A graduate of the University of New Hampshire, Kelly began his career as a researcher and booker for ABC's "Good Morning America" before moving on to reporting jobs at the Cincinnati Enquirer and Baltimore Sun. He later served as the Midwest stringer for the Boston Globe and wrote for such magazines as GQ, Esquire and Playboy.

He had a talent for getting attention. As a Sun reporter in 1987, Kelly caused a stir by taking Fawn Hall, the Oliver North secretary caught up in the Iran-contra affair, to the White House Correspondents' Dinner. After joining the New York Times, he poked fun at the new first lady's spiritual journey in a 1993 magazine cover story titled "Saint Hillary."

Kelly went to the Persian Gulf a dozen years ago to follow his wife, then a CNN producer, and returned to Baghdad after Saddam Hussein's defeat. His evocative, sometimes emotional dispatches for the New Republic won a National Magazine Award, and he wrote a well-received book called "Martyrs' Day."

In a March 1991 piece for the New Republic, Kelly wrote from Kuwait: "I had thought from the moment the first bomb dropped on Baghdad that the matchup between Saddam Hussein and a good portion of the civilized world was wildly one-sided, but the staggering, lunatic scope of the disaster he visited on his people did not actually bring tears to my eyes until the moment here, on the third day of the ground war, when I took my first, and I hope my last, prisoners of war."

Kelly also covered the fighting in Bosnia for the New Yorker in 1995. His last column was published by The Post on Wednesday. It began:

"Near the crest of the bridge across the Euphrates that Task Force 3-69 Armor of the 1st Brigade of the 3rd Infantry Division seized yesterday afternoon was a body that lay twisted from its fall. He had been an old man -- poor, not a regular soldier -- judging from his clothes. He was lying on his back, not far from one of several burning skeletons of the small trucks that Saddam Hussein's willing and unwilling irregulars employed. The tanks and Bradleys and Humvees and bulldozers and rocket launchers, and all the rest of the massive stuff that makes up the U.S. Army on the march, rumbled past him, pushing on."

Kelly, embedded with the 3rd Infantry Division, told ABC's "Nightline" last month that he felt "some sense of danger" in covering the war, but he didn't regard the risk as unduly high.Colleagues recalled Michael Kelly as a gifted writer, inspiring editor and "a real role model."