KARBALA, Iraq (Reuters) -- Thousands of Iraqi Shi'ite pilgrims are nearing the end of a major rite, while others were already beginning long treks home during which they might again be vulnerable to attack.
Defying the suicide bombs that have threatened gatherings of Shi'ite Muslims since the 2003 U.S.-led invasion toppled the Sunni-led government of Saddam Hussein, hundreds of thousands if not millions poured into the holy city of Karbala for Arbain.
Beating heads and chests in ritual mourning for Hussein, the Prophet Muhammad's grandson, who died in a 7th-century battle, pilgrims streamed through the Imam Hussein mosque in the city 80 kilometers south of Baghdad in an endless procession.
The rite culminates at Hussein's gilded grave, where worshippers weep and pray, while giant television screens in the city show films of Hussein's deeds and preachers chant and recount Shi'ite tales through loudspeakers.
Officials in Karbala say that around 10 million Shi'ite pilgrims flooded the city this year for the annual ritual, once suppressed like other Shi'ite gatherings under Hussein and which marks the end of 40 days of mourning for Hussein.
While other parts of Iraq seemed eerily empty on February 16, that number seemed huge given Iraq's total population of around 28 million, 60 percent of whom are Shi'ite.
A City Overwhelmed
But Karbala was clearly overwhelmed. Its few hotels overflowed with guests, water ran dry in public toilets, the elderly and the weak fainted in droves from the crush of the crowds, and thousands slept in the streets or in mosques.
"I walked from Al-Basrah to Karbala, and when I entered this crowded area two days ago I lost my wife. Today, I found her by chance," said Wisam Jabur, 38, a civil servant. "I couldn't phone her because the cellphone network was so bad."
Raghad Mohammed, a pilgrim from Baghdad, said he was concerned about how to get home, and was exhausted after walking all the way to Karbala and then spending days without sleep.
Worries about the way home were echoed by many.
"The security situation is not 100 percent stable," said engineer Inas Yunis, recalling a suicide bombing on February 13 that killed 42 people on a route to Karbala and other attacks by suspected Sunni Islamist insurgents, like Al-Qaeda, who see Shi'ites as heretics.
"The biggest concern is how to go back home. There will be a transport crisis," Yunis said.
Despite a sharp drop in violence in Iraq in recent months, security for the Arbain ritual was tight. About 30,000 Iraqi soldiers and police guarded Karbala and all pilgrims were searched before they were allowed near the revered shrine.
The measures did not prevent the February 13 suicide blast, nor a roadside bomb on February 12 that killed eight people near the Imam Hussein mosque. An attempted suicide bombing near Karbala was foiled on February 14 after police pounced on a would-be attacker.
February 15 passed without incident in Karbala, leaving the route home, when the pilgrims will again be dispersed and vulnerable, as the remaining challenge for security forces.
U.S. officials say attacks are attempts to reignite the sectarian slaughter that almost tore Iraq apart.
Politics may also be a factor after allies of Shi'ite Prime Minister Nuri al-Maliki posted gains in January 31 local elections.
That set Maliki's Dawa Party up for a muscular run in parliamentary polls at the end of the year, and rivals may want to undermine the perception that he can take some credit for the reduction in bloodshed, security sources say.