chanted, "What do we want? Troops out. When do we want it? Now."

Army veteran Justin Cliburn, 25, of Lawton, Okla., was among a contingent of Iraq veterans in attendance.

"We're occupying a people who do not want us there," Cliburn said of Iraq. "We're here to show that it isn't just a bunch of old hippies from the 60s who are against this war."

Counterprotesters lined the sidewalks behind metal barricades. There were some heated shouting matches between the two sides.

The arrests came after protesters lay down on the Capitol lawn in what they called a "die in" - with signs on top of their bodies to represent soldiers killed in Iraq. When police took no action, some of the protesters started climbing over a barricade at the foot of the Capitol steps.

Many were arrested without a struggle after they jumped over the waist-high barrier. But some grew angry as police with shields and riot gear attempted to push them back. At least two people were showered with chemical spray. Protesters responded by throwing signs and chanting: "Shame on you."

The number of arrests by Capitol Police on Saturday was much higher than previous anti-war rallies in Washington this year. Five people were arrested at a protest outside the Pentagon in March when they walked onto a bridge that had been closed off to accommodate the demonstration, then refused to leave. And at a rally in January, about 50 demonstrators blocked a street near the Capitol, but they were dispersed without arrests.

The protesters gathered earlier Saturday near the White House in Lafayette Park with signs saying "End the war now" and calling for President Bush's impeachment. The rally was organized by the ANSWER Coalition and other groups.

Organizers estimated that nearly 100,000 people attended the rally and march. That number could not be confirmed; police did not give their own estimate. A permit for the march obtained in advance by the ANSWER Coalition had projected 10,000.

Anti-war activist Cindy Sheehan told the crowd is was time to be assertive.

"It's time to lay our bodies on the line and say we've had enough," she said. "It's time to shut this city down."

About 13 blocks away, nearly 1,000 counterprotesters gathered near the Washington Monument, frequently erupting in chants of "U-S-A" and waving American flags.

Retired Air Force Lt. Col. Robert "Buzz" Patterson, speaking from a stage to crowds clad in camouflage, American flag bandanas and Harley Davidson jackets, said he wanted to send three messages.

"Congress, quit playing games with our troops. Terrorists, we will find you and kill you," he said. "And to our troops, we're here for you, and we support you."

Associated Press writer Christine Simmons contributed to this report.