John McNamara never believed the 2003 invasion of Iraq was justified, but as a soldier in an Army transportation unit, he dutifully took part in a war he did not support.

When he left Iraq six months later, he was just happy that he survived.

Now out of the military, McNamara donned his desert camouflage uniform again yesterday to march against the war in which he served.

"Being part of something I didn't agree with didn't sit well in my stomach," said McNamara, 25, of Boston, carrying one corner of a banner for a small, fledgling group called Iraq Veterans Against the War. "Joining this protest, it is the only way I can help end it. It feels good."

Like McNamara, many marching in Washington's streets yesterday have opposed the war in Iraq from the beginning. The protest drew a broad cross section of young and old, veteran activists and first-timers. But of more than 50 marchers interviewed, nearly all said their convictions deepened, not changed, as the war progressed. What they shared was the belief that their suspicions about President Bush and the war had been right all along.

So there was a quiet, often angry determination in the crowd, with little of the jovial street theater that marks much political protest. Most placards did not simply call to bring troops home. At turns they labeled Bush a liar, a traitor, a fascist, a coward and a war criminal worthy of impeachment. Some asked plaintively, "Where's the outrage?"

"I'm very angry," said Amy Campbell-Pitts, 28, of Nashville, whose husband, Jason, is an Army medic. A veteran of Afghanistan, he just left on a deployment to Iraq, kept in uniform under a stop-loss program limiting when volunteers can quit the military. "Send my husband home," read the placard she carried.

"It's the stop-loss that ticks me off," said Campbell-Pitts, whose honeymoon was interrupted by a deployment briefing. "He kept his word, and the government doesn't have to keep its."

Nearby, Judy Linehan led more than 300 military family members marching against the war. The mother of an Army major from Olympia, Wash., Linehan said Americans are more receptive to the antiwar message than ever. The war's more ardent supporters remain committed, she said, but added, "I can see a change in people who were on the fence."

Judy Munro-Leighton of Louisville began organizing protests three years ago, before the war even began. The Louisville Peace Action Community staffed a booth two years ago at the Kentucky State Fair, she said, and supporters of the war stopped to berate them. That rarely happens now, she said.

"We get much more support," said Munro-Leighton, a history teacher who was among 100 people who traveled from Louisville on two protest-bound buses. "We even started an impromptu petition to end the war."

For many, peace was a religious mandate. Banners identified marchers as United Methodists for Peace, Benedictines for Peace and the Presbyterian Peace Fellowship.

"It's just such a tragedy," said Vernon Ware, head of Howard Divinity Students for Peace and Justice. "We have a divinity school student who was called back into the Reserves. We have strong support for our troops. They're people we know."

In addition to banners, props were used to convey some protesters' messages. John Lake of Brooklyn, N.Y., brought enough flags to cover 75 cardboard "coffins." Another seven flag-draped coffins were carried by a small group of high school students and their relatives from Goldens Bridge, N.Y.

"I've been following the war since it started when I was in the eighth grade," said Bettina Warshaw, a high school junior who carried one symbolic coffin. "Now I'm old enough to come protest."

In one of the few confrontations, tempers flared near a tent erected by supporters of Cindy Sheehan, the mother of a soldier killed in Iraq who camped outside Bush's Texas ranch this summer. Six parents came by to cut their children's photos from a poster showing the faces of the first 1,000 Americans to die in the Iraq conflict.

"My son wouldn't want his face here," said Charlotte Smette of Makoti, N.D., trembling in her husband's arms with angry tears. Around his neck, Doug Smette wore a wooden cross and the dog tags of his son, Keith, who was killed in Iraq on Jan. 24, 2004.

A few feet away, protesters had laid out rows of empty boots embellished with small U.S. flags and white candles next to a tableau of small white crosses.

"This, to me, is disrespectful," said John Wroblewski of Jefferson Township, N.J., whose son, John, served in the Marines and was killed in a firefight in Iraq.

Many of the soldiers Adam Reuter served with in Iraq during a 10-month deployment would see it the same way. They remain supportive of the war and its goals, he said. But he never disguised his opposition.

"I didn't join up to go to Iraq," said Reuter, 20, of Atlanta, who enlisted one month after the 2001 attacks on the World Trade Center and the Pentagon. "I joined to hopefully hold those responsible for the attacks of 9/11."

Now a member of Iraq Veterans Against the War, Reuter said he thinks more in the military are questioning the war. At yesterday's march, he said, 60 veterans joined the protest group.