U.S. Marines continued their withdrawal from Baghdad on Easter Sunday and journeyed south while U.S. Army units took over. Taking a break from manning some posts, some soldiers even attended Easter services.

Iraq's Shiite Muslims revived one of their own holy traditions long repressed by former Iraqi president Saddam Hussein.

President Bush planned to attend Easter services with soldiers at Fort Hood in Texas, then meet with two Apache helicopter crewmen who were freed a week ago from captivity in Iraq.

Former President Bush and his wife, Barbara, may attend the event.

Army Chief Warrant Officer Ronald Young Jr. and Army Chief Warrant Officer David Williams were among seven former POWs who returned home Saturday to a joyous welcome at Fort Hood and Fort Bliss.

"This almost makes me as nervous as being shot at," Young said. "We really appreciate the support."

Two U.S. congressmen met with Syrian President Bashar Assad to discuss recent U.S. allegations that Syria is harboring Iraqi regime members.

Assad told Reps. Nick Rahall, D-W.Va., and Darrell Issa, R-Calif., who traveled to Syria, that his government won't give asylum to Iraqis wanted for war crimes and will expel any who cross into Syria. Rahall and Issa were the first American officials to meet Assad since the recent escalation of U.S.-Syrian tensions.

U.S. Secretary of State Colin Powell will make that trip soon to talk about that and reports that Syria is producing chemical weapons.

"We have many positive messages to Washington," Issa told Reuters. "Assad went out of his way in being positive."

President Bush said Sunday that Syria is "getting the message" that it should help the United States capture fleeing Iraqi leaders.

"I'm confident the Syrian government has heard us," Bush said after attending Easter church services at Fort Hood near his central Texas ranch. "I believe it when they say they want to cooperate with us."

At the Vatican, Pope John Paul II, in his Easter message, said the Iraqi people themselves should determine their country's future.

"Peace in Iraq!" proclaimed the pontiff, drawing cheers from a rain-soaked crowd in St. Peter's Square. "With the support of the international community, may the Iraqi people become the protagonists of their collective rebuilding of their country."

Under the military repositioning plan of U.S. troops in Iraq, all Marines who were in east Baghdad are heading toward the southern half of the country, while Army units will control the Baghdad and the northern half of the country.

The 1st Marine Division elements were relieved by the Army's 3rd Infantry Division on Saturday.

Marines have also turned over the Civil-Military Operations Center at the Palestine Hotel in Baghdad. The CMOC directed civil-military operations in four major functional areas, including electricity, law enforcement, water and sanitation, and medical care.

The shift will greatly cut back on the number of American troops in Baghdad.

Also Sunday, physicians and nurses at Nasiriyah's main hospital said in a television interview that they defied Iraqi leaders to bring food, clothes and medicine from their own limited supplies to Army Pfc. Jessica Lynch while she was held captive there. Lynch was part of the 507th Maintenance Unit that was ambushed late last month by Iraqi soldiers.

Dr. Ahmed Muhsin said Lynch's guards beat her and tried to stop doctors from checking her more than twice a day. Lynch was rescued in a commando raid April 1 and is recuperating in Washington.

Soldiers met Sunday with community leaders and discussed security concerns. A U.S.-run radio station - Information Radio - read a statement announcing an 11 p.m.-6 a.m. curfew.

"Anyone who violates this curfew will put himself in danger," one announcer said. Another advised people not to carry weapons "because you might be considered a threat to coalition forces."

The city's stores are open and the streets were bustling. Many people were cleaning up debris from the war.

Longtime exile Mohammed Mohsen al-Zubaidi, who says he's in charge of Baghdad, said that Iraq's new constitution would be derived from Islamic law and promised to try anyone whose "hands are stained with the blood of the Iraqi people."

Al-Zubaidi is a deputy of Ahmad Chalabi, a top figure in the Iraqi National Congress, backed by Washington. One of his associates said police discovered documents from Saddam's intelligence service about "people responsible for killing innocent people all over the world."

Chalabi said Iraq needed a constitution that would deter religious parties from trying to establish a permanent Islamic state.

"There is a role for Islamic religious parties, for they have some constituencies. But they are not going to be forcing any agenda or forcing a theocracy on the Iraqi people," Chalabi said on ABC's This Week. "We do not think that an election, one election, should determine permanently the nature of the state in Iraq."

But on Sunday, millions of Shiites were marching Sunday toward the holy cities of Karbala and Najaf on an annual religious pilgrimage that was discouraged for decades by Saddam. Shiites, 60 percent of Iraq's 24 million people, were brutally repressed under Saddam's regime, which was dominated by Sunni Muslims.

For Shiites in their 20s and 30s, it was their first time marching. For older men like Hussein Saman, 48, imprisoned for 11 years for openly practicing Shiite rituals, it was his first pilgrimage since the 1970s.

"In the days of Saddam, if anyone did this march, he was killed," said Saman.

As many as 2 million Shiites from Iraq, Iran and other countries in the Middle East are expected to converge on the two holy cities.

One leading Shiite cleric — Ayatollah Mohammed Baqir al-Hakim, head of an Iran-based anti-Saddam movement — suggested that marchers express their rejection of the U.S. military presence.

U.S. troops tried to keep a low profile, even as they stockpiled emergency food and water or the pilgrims.

"We don't want to interfere with the pilgrimage.... But we are prepared for the worst," said Maj. James M. Bozeman of the 82nd Airborne Division.

The pilgrimage marks 40 days after the date on which Hussein — a grandson of the Prophet Muhammad — is believed to have been killed in Karbala over 1,300 year ago.

Easter services were offered at several U.S. military for American Christian soldiers.

At an Iraqi air defense school, 30 soldiers of the 101st Airborne gathered - camouflage Bibles in hand - for a service conducted by Chaplain Maj. John Routzhan.

One soldier said his wife's pregnancy is going well. Another said he was celebrating his 36th birthday. Sgt. 1st Class John Stroman, 40, of Orangeburg, S.C., was thankful they had survived the war.

"We had a hard time when we first came over here. But He protected us from all harm and danger," Stroman said.

U.S. soldiers waiting for orders to go into Iraq celebrated the day in a camp in northern Kuwait with prayers and thoughts of their families back at home.

"We probably never thought we would be celebrating Easter in the desert, but God is with us and He will be with us wherever we go," Sergeant Major Curtis Davis, a Baptist preacher, told soldiers from the 4th Infantry Division, reports Reuters.

"There is a purpose and a reason for why you are all over here," he said. "God has chosen us for a mission. Be strong and courageous."

Australia's foreign minister, Alexander Downer, said Sunday that coalition officials are finishing a proclamation — to be issued in the next few days — formally declaring the war over.

"Obviously it has to be absolutely accurate legally," Downer told Australian television's Seven Network. "It also has to be a proclamation that strikes the right political tone."

Australia has 2,000 military personnel in the coalition.

Fox News' Mike Emanuel and The Associated Press contributed to this report.