The pilgrimage is one of the most important events on the Shiite calendar, reports CBS News correspondent Allen Pizzey. But conspicuous by its absence was security.
After a temporary fall in body counts and bombings brought a statement from the government that the new security operation was "a shining success," the past two days are a horrific reminder that full-scale sectarian war is as close as security is a distant hope.
U.S. forces, too, continue to tally losses at the hands of extremists despite signs of more successful raids against bases and weapon stockpiles.
The military said nine soldiers were killed Monday in two separate roadside bombings north of Baghdad, making it the deadliest day for U.S. troops in Iraq in nearly a month.
In Baghdad, U.S. forces continued their push into Sadr City, home to 2.5 million of the city's poorest residents as well as fighters loyal to anti-American cleric Muqtada al-Sadr. Some 600 American soldiers searched the neighborhood's northwest quadrant, knocking on doors and searching homes, according to an Associated Press reporter traveling with them.
As the mission, called Operation Imposing Law, has progressed, Iraqi troops have outnumbered Americans 2-to-1, the exact opposite of previous missions, adds Pizzey from Baghdad.
The U.S. forces are seeking a "reconciliatory approach" to avoid sparking a backlash on the streets, said Col. Richard Kim. One small gesture seemed to offer appreciation: a child offering soldiers ice cream bars.
"A brutal massacre against people who are only practicing their faith" was how Shiite lawmaker Sami al-Askari described the Hillah attacks, which injured at least 157 people.
Dr. Mohammed al-Temimi, at Hillah's main hospital, said some of injuries were critical and the death toll could rise.
The Hillah strike came after gunmen and bombers hit group after group of Shiite pilgrims elsewhere — some in buses and other making the traditional trek on foot to the shrine city of Karbala, about 50 miles south of Baghdad. At least 24 were killed in those attacks, including four relatives of a prominent Shiite lawmaker, Mohammed Mahdi al-Bayati.
This weekend, huge crowds of Shiite worshippers will gather for rites marking the end of a 40-day mourning period for the death of Imam Hussein, the grandson of the Prophet Muhammad, who died near Karbala in a famed seventh-century battle.
In Hillah, southeast of Karbala, a long line of pilgrims marched toward a bridge checkpoint on the edge of the city. Food and cool drinks were distributed at nearby tents.
The first suicide bomber killed dozens and touched off a mad dash of people away from the bridge, said witness Salim Mohammed Ali Abbas. As the fleeing crowd grew thicker, another suicide bomber among them blew himself apart.
A police commander, Brig. Gen. Othman al-Ghanemi, said the attackers joined the procession outside Hillah and waiting until it reached the checkpoint bottleneck to try to maximize the damage.
"In an instant, bodies were set ablaze, people were running and the ground was mixed with teapots, kettles and other supplies for pilgrims," said Mahdi Kadim, one of the survivors.
In other developments:
Hours after the attack, boys used long-handled squeegees to push pools of blood off the road. The shoes and sandals of the victims were gathered in haphazard piles.
"The government bears some responsibility for this," complained a Shiite parliament member, Bahaa al-Araji. "It has not provided enough security to protect the pilgrims."
In the past two years, the powerful Mahdi army militia watched over pilgrimages to Karbala. But the group agreed to put down its arms under intense pressure from the government, which wanted to avoid any confrontations with U.S.-led forces during a massive Baghdad security crackdown launched last month.
"This year, things are sadly different," said al-Araji.
But Hillah has seen worse. In February 2005, a suicide car bomber hit mostly Shiite police recruits, killing 125 people.
U.S. forces suffered their deadliest day since Feb. 7, when 11 troops were killed, seven when their helicopter was shot down north of Fallujah and four others in combat operations.
The military said six soldiers of the 82nd Airborne Division were killed in a bombing in Salahuddin Province. It was the single largest loss of life in the past three years of combat for the Fort Bragg, North Carolina-based unit, said division spokesman Maj. Tom Earnhardt.
Another three soldiers died the same day in a roadside bomb attack in Diyala province northeast of Baghdad.
Both provinces are Sunni-dominated and have seen a rise in violence since additional U.S. forces moved into Baghdad as part of security sweeps. The Pentagon has pledged 17,500 additional troops for the Iraqi capital.
In a speech to the American Legion in Washington, President Bush said it was "too early to judge the success" of the Baghdad crackdown.
"But even at this early hour there are some encouraging signs," Mr. Bush said. Still, he added: "There are no shortcuts in Iraq."
In the northern city of Mosul, an estimated 140 inmates broke out of an Iraqi-guarded prison, said Brig. Gen. Mohammad al-Wakaa. He gave no other details, but appealed for U.S. helicopters to join the hunt for the fugitives.
Saddam Hussein's nephew, Ayman Sabaawi, escaped from the same prison in December. He was serving a life sentence for financing insurgents and possessing bombs, and remains at large.
In Baghdad, parliament failed to reconvene as scheduled after only about two dozen of the 275 lawmakers showed up. Political leaders claim that talks between various parties kept the deputies away.
But it was seen as another sign of political stagnation when key issues are facing the parliament, including a proposed law to divide Iraq's oil revenue between its three main groups: Sunnis, Shiites and the northern Kurds.
The nine U.S. deaths brought to 20 the number of Americans killed in Iraq this month. At least 3,184 members of the U.S. military have died since the beginning of the Iraq war in March 2003, according to an Associated Press count. The figure includes seven military civilians. At least 2,561 died as a result of hostile action, according to the military's numbers.