WASHINGTON - Denouncing a conflict entering its fifth year, protesters raised their voices Saturday against U.S. policy in Iraq and marched by the thousands to the Pentagon in the footsteps of an epic demonstration four decades ago against another divisive war.

A counterprotest shadowed the anti-war crowd on a day of dueling signs and sentiments such as "Illegal Combat" and "Peace Through Strength," and songs like "The Battle Hymn of the Republic" and "War (What's It Good For?)."

A group of Washington County residents who took part in the counterprotest said the experience Saturday was a positive one.

For Clear Spring resident and Vietnam War veteran Larry Michael, the counterprotest - his first - was a way for him to express support for the troops.

"I can remember those days when I got the newspaper from home about the protests against us and the war ... That's all we heard was protests against the war ... It takes the wind out of your sails," Michael, 60, said.

Although Michael said he didn't meet up with anyone he knew, he said he did get to speak with other veterans about their feelings on Iraq.

He feels the war must be won. Showing weakness to the opposition will only make them stronger, he said.

Michael traveled back from the demonstration in a Chevrolet Blazer with five friends, including Judy Warner, 63, of Rohrersville, Ann Corcoran, 56, of Keedysville and Mark Collins, 48, of Keedysville.

Warner said she was surprised that there were not more protestors against the war at the demonstration. Warner, who said she helped carry a banner that said "Marylanders Support our Troops, said she met people from Texas and Maine.

Thousands crossed the Memorial Bridge over the Potomac River from the Lincoln Memorial to rally near the Pentagon. Smaller protests were organized across the country and held abroad, stretching to Tuesday's four-year anniversary of the Iraq invasion.

Locally, Jefferson County resident Liz McGowen said anti-war demonstrators stand at the main intersection of Shepherdstown in the morning and evening today to pass out addressed and stamped postcards to U.S. Rep. Shelley Moore Capito, R-West Virginia, encouraging others to write her with their concerns.

McGowen said she chose not to go to the Washington demonstration and instead focus on local activism. The group to which she belongs, The Eastern Panhandle Costs of War Group, focuses on emphasizing the number of American and Iraqi lives lost in the war and the cost to sustain it, which she said could be used to fund domestic issues such as health care and education.

"We are definitely supporting the troops by getting them home and getting them out of harm's way," McGowen said.

At the Washington demonstration, speakers criticized the Bush administration at every turn but blamed congressional Democrats, too, for refusing to cut off money for the war.

"This is a bipartisan war," New York City labor activist Michael Letwin told the crowd. "The Democratic party cannot be trusted to end it." Letwin said the key to ending the war soon is to bring more troops and their families into the protest movement.

People traveled from afar in stormy weather to join the march.

"Too many people have died and it doesn't solve anything," said Ann O'Grady, who drove through snow with her husband, Tom, and two children, 13 and 10, from Athens, Ohio. "I feel bad carrying out my daily activities while people are suffering, Americans and Iraqis."

Retired Marine Jeff Carroll, 47, an electrician in Milton, Del., held a sign saying: "Proud of our soldiers, ashamed of our president." Carroll said he served in Lebanon when the Marine barracks was bombed in a deadly attack in 1983, and thinks the U.S. should be focusing on Afghanistan and Osama bin Laden instead of Iraq. "We're fighting the wrong country."

Police on horseback and foot separated the two groups of demonstrators, who shouted at each other from opposite sides of Constitution Avenue in view of the Lincoln Memorial before the anti-war group marched. Barriers also kept them apart.

Protesters walked in a blustery, cold wind across the Potomac River with motorcycles clearing their way and police boats and helicopters watching.

Police no longer give official estimates but said privately that perhaps 10,000 to 20,000 anti-war demonstrators marched, with a smaller but still sizable number of counterprotesters also out in force. A January anti-war protest, with fine weather and celebrities on the stage including Vietnam-era activist Jane Fonda, drew more people.

The anti-war group Saturday carried signs saying "U.S. Out of Iraq Now," "Stop Iraq War, No Iran War, Impeach." The other side carried signs saying "al-Qaida Appeasers On Parade" and "Fight Jihad Not GIs."

Protesters met at the starting point of the Oct. 21, 1967, march on the Pentagon, which began peacefully but turned ugly in clashes between authorities and more radical elements of the estimated crowd of 50,000 on the plaza in front of the Defense Department's headquarters. More than 600 were arrested that day.

That protest has lived on in the popular imagination because of the crowd's attempts to lift the Pentagon off the ground with their chants; they fell short of their fanciful goal.

Organizers of the Saturday protest did not anticipate numbers comparable to those of the Vietnam era.

Veterans, some from the Rolling Thunder motorcycle group, lined up at the Vietnam Veterans Memorial and waved U.S, POW-MIA and military-unit flags. Not all were committed to the U.S. course in Iraq, however.

"I'm not sure I'm in support of the war," said William "Skip" Publicover of Charleston, S.C., who was a swift boat gunner in Vietnam and lost two friends whose names are etched on the memorial's wall. "I learned in Vietnam that it's difficult if not impossible to win the hearts and minds of the people."

But Larry Stimeling, 57, a Vietnam veteran from Morton, Ill., said the loss of public support for the Iraq war mirrors what happened in Vietnam and leaves troops without the backing they need.

"We didn't lose the war in Vietnam, we lost it right here on this same ground," he said, pointing to the grass on the National Mall. "It's the same thing now."

Henry Sowell, 22, Raleigh N.C., who fought with the Marines in Iraq in 2005, asserted that anti-war protesters were "taking away what my buddies died for and what I fought for."

Some active-duty service members joined the anti-war protest, following rules that allow them to demonstrate but limit what they can say.

Petty Officer Jonathan Hutto, who is on active duty with the Navy, told the crowd that the people had voted against the war in the November elections and "we're here to cash the check."

Rallies also were planned in Los Angeles, Denver, Chicago, Oklahoma City, Hartford, Conn., and Lincoln, Neb.

Overseas, more than 3,000 people protested peacefully in Istanbul, Turkey, and about 1,000 in Athens, Greece.