At the Zurbatiyah crossing, under a blazing sun, pilgrims clad in black clutched portraits of their slain leader Ali Khamenei. Some stamped on an image of Donald Trump; others raised fists or flashed victory signs. Large fans sprayed mist to cool the heat as the crowd passed pictures of Khamenei, his son and successor Mujtaba, and commanders from Iran’s so-called “axis of resistance”. Amir, a 55-year-old pick-up driver from Alborz province, has made the journey for years, but this time, he said, “the difference is that we are at war. Now, the United States is attacking us… yet this crowd that you see has left everything behind.”

Arbaeen marks the fortieth day of mourning for Imam Hussein, the Prophet Mohammed’s grandson, whose death in battle in 680 is central to Shia Islam. It is one of the world’s largest religious gatherings, with millions walking to his shrine in Karbala. This year’s pilgrimage is the first since a US-Israeli attack on Iran on 28 February killed Khamenei in the opening strikes. The war erupted only weeks after Iranian authorities crushed widespread anti-government protests over the cost of living. Hours before Amir entered Iraq, US-Saudi strikes killed 20 militants, including five Iranians, across seven Iraqi provinces, drawing the host country deeper into the conflict.

At the border, pilgrims spoke of loss and resolve. Fatemeh Moradi, 52, from Tehran, said she was walking “on behalf of our martyred leader and on behalf of all the martyrs”. She had lost many relatives in the war, but for her “martyrdom is a sense of pride”. Hamed Kameli, a 39-year-old electrician from Qom making his first Arbaeen in seven years, said, “Because of the aggression against my country, our presence here is certainly very different from previous years. We will never give up our country … we will avenge our leader.” Along the route, portraits of Qassem Soleimani, Abu Mahdi al-Muhandis and Hassan Nasrallah lined the roads, and some pilgrims chanted slogans in support of the Islamic Republic.

The sheer scale of the movement was captured in official tallies. By Thursday, over two million of the 2.4 million registered pilgrims had crossed into Iraq “in safe and sound condition”, according to police commander General Muhammad Sharafi, with half a million already returned. At the Mehran crossing alone, nearly 1.9 million had passed since the start of the month of Safar, and more than 266,000 crossings were recorded in a single 24-hour period. Iraqi authorities said around 3.5 million foreign pilgrims had entered the country. On the “Ya Hussein” road between Najaf and Karbala, processions offered food, water and medical care, while Iranian health teams screened over 842,000 people for respiratory and food-borne illnesses.

Early Saturday, the pilgrimage was jolted by three traffic accidents on roads leading to Najaf. A bus overturned on the Baghdad–Najaf highway, injuring 50 people; nine suffered fractures, three were in critical condition and one was in a coma. A van caught fire after rolling over, sending six to hospital. A minibus collided with a Dodge, leaving 24 injured, 22 of them Iranian. Red Crescent teams, working alongside Iraqi emergency services, transferred the wounded to local hospitals. The accidents underscored the physical risks of a mass movement already freighted with grief. At Zurbatiyah, Amir complained that the economy was suffering, but added, “We are standing against them, and we will resist, even if we have to survive on dry bread.” As the pilgrims moved deeper into Iraq, the portraits of the dead leader went with them, held aloft in the heat.