Security forces in Iraq were on high alert for any attacks similar to what has taken place during prior pilgrimages and caused mass casualties in previous years.
The presence in Iraq of the Islamic State the ultra-hardline militants who have swept through northern Iraq earlier in 2014 raises the possibility there could be widespread bloodshed as the crowds in the country began to swell.
IS is seen as being more ruthless than al-Qaeda its predecessor and believes that Shiites are infidels and deserve to be killed.
IS has claimed responsibility for a number of suicide bombings that claimed the lives of people in the majority sect.
Security in this event had been very tight since mortar attacks and suicide bombers, suspected to be members of al-Qaeda, killed more than 171 at the Ashoura pilgrimage in 2004.
Shiites are commemorating the slaying of Hussein the grandson of Prophet Mohammad in AD 680 at the battle of Karbala.
Hundreds of thousands of people gather outside the Imam Hussein shrine and shout, “Hussein, Hussein, Hussein.”
At the ritual the Shiites hit their heads as well as chests, with some gashing their heads with swords in order to show grief and echo Imam Hussein’s suffering.
In years past, suicide bombers have posed as the pilgrims to infiltrate large crowds. Militants have also fired mortar rounds at the groups just outside Karbala.
Under the secular rule of Saddam Hussein, these types of display had been banned since the country was ruled for the most part by Sunnis and the Baathe Party.
Since 2003, when the invasion of U.S. forces toppled the dictator, Shiites have dominated the governments in Iraq, but practicing their faith openly at large public gatherings puts the country’s majority sect at risk from suicide bombers.
Attacks by IS on Shiites have helped to return violence to its alarming levels seen during 2006-07, which was the peak of the sectarian civil war.
After Haider al-Abadi the Prime Minister and Shiite took control three months ago, he promised to heal the divisions and to unite the country against the IS.