WASHINGTON -- Tens of thousands of anti-war activists faced police in riot gear at the Pentagon on Saturday to denounce U.S. policy in Iraq.

Police pushed the protestors back after a raucous march from the National Mall, participants said. People on both sides of the debate shouted at each other, while barriers and police on horseback kept them apart.

Addressing the rally, New York City labor activist Michael Letwin told the crowd the was a "bipartisan" effort, saying "the Democratic party cannot be trusted to end it."

One retired Marine held a sign saying: "Proud of our soldiers, ashamed of our president."

Saturday's march followed the same path as a Vietnam War protest 40 years ago.

Thousands of protesters crossed the Memorial Bridge to rally as close to the Pentagon as they could get. Smaller protests were organized across the country and held abroad, stretching to Tuesday's four-year anniversary of the Iraq invasion.

The weekend protests got under way Friday night, with more than 200 people arrested outside the White House.

At least 3,000 people opposed to the war gathered at Washington National Cathedral for a prayer service. They later marched through the cold wind to the White House.

Several hundred had volunteered to risk arrest by standing and praying on the sidewalk directly in front of the White House. Protest guidelines require demonstrators to continue moving while on the White House sidewalk. President George W. Bush wasn't there. He is at Camp David this weekend.

According to U.S. Park Police, 222 protesters were arrested Friday night. They face $100 fines, police said.

Protestor Jim Wallis, a preacher, said the war in Iraq has hurt Christianity because millions of people around the world believe it's a religious war. He said Christians need to clear up the confusion.

There was no word on arrests or the total number of protesters who rallied in D.C. on Saturday.