WASHINGTON —  Cindy Sheehan (search), the California woman who became a leader of the anti-war movement following her son's death in Iraq, was arrested Monday along with dozens of others protesting outside the White House.

Sheehan, carrying a photo of her son in his Army uniform, was among hundreds of protesters who marched around the White House and then down the two-block pedestrian walkway on Pennsylvania Avenue. When they reached the front of the White House, dozens sat down -- knowing they would be arrested -- and began singing and chanting "Stop the war now!"

Police warned them three times that they were breaking the law by failing to move along, then began making arrests. One man climbed over the White House fence and was quickly subdued by Secret Service agents.

Sheehan, 48, was the first taken into custody. She smiled as she was carried to the curb, then stood up and walked to a police vehicle while protesters chanted, "The whole world is watching."

About 50 people were arrested in the first hour, with dozens of others waiting to be taken away. All cooperated with police.

Sheehan was among several hundred demonstrators who marched around the White House on Monday and then stopped in front and began singing and chanting "Stop the war now!"

The demonstration is part of a broader anti-war effort on Capitol Hill organized by United for Peace and Justice, an umbrella group. Representatives from anti-war groups were meeting Monday with members of Congress to urge them to work to end the war and bring home the troops.

The protest following a massive demonstration Saturday on the National Mall that drew a crowd of 100,000 or more, the largest such gathering in the capital since the war began in March 2003.

On Sunday, a rally supporting the war drew roughly 500 participants. Speakers included veterans of World War II and the war in Iraq, as well as family members of soldiers killed in Iraq.

"I would like to say to Cindy Sheehan and her supporters don't be a group of unthinking lemmings. It's not pretty," said Mitzy Kenny (search) of Ridgeley, W.Va., whose husband died in Iraq last year. The anti-war demonstrations "can affect the war in a really negative way. It gives the enemy hope."