Shiite pilgrims from Iraq and around the world are to throng Iraq's shrine city of Karbala on Thursday for the climax of Arbaeen mourning rituals amid tight security for fear of militant attacks.
Over the past 10 days, the annual commemoration ceremonies are expected to have drawn up to 15 million pilgrims braving the threat of deadly violence by Sunni insurgents targeting the Shiite community in recent weeks.
Arbaeen marks 40 days after the Ashura anniversary commemorating the slaying of Imam Hussein, one of Shiite Islam's most revered figures, by the armies of the caliph Yazid in 680 AD.
Sad songs blared from loudspeakers throughout the city and black flags fluttered alongside pictures of Hussein and his half-brother Imam Abbas, both of whom are buried in the city.
"We are defying terrorism, and we are following the example of Karbala in sacrifice and redemption," said 40-year-old Mohammed Swadi, who noted that he had walked for 12 days from the southern port city of Basra for the occasion.
"This is not much when it comes to expressing our love for Imam Hussein."
Officials expect some 15 million worshippers to have passed through the city, which lies 110 kilometres (70 miles) south of Baghdad, by the end of the commemorations.
Among them will be around 600,000 pilgrims from 30 different countries, leaving all of the city's 700 hotels packed to the brim.
The threat of insurgent attacks has spurred authorities to deploy 35,000 soldiers and policemen to Karbala, including 2,500 policewomen at checkpoints across the city, with aerial surveillance also watching over pilgrims.
Attacks on Shiites in just the past week have left at least 12 people dead, including an explosion along the route from Baghdad to Karbala on Wednesday that killed two pilgrims who were on the traditional walk to the shrine city.
Shiites make up around 15 percent of Muslims worldwide. They represent the majority populations in Iraq, Iran and Bahrain and form significant communities in Afghanistan, Lebanon, Pakistan, India and Saudi Arabia.