Asked by their teacher to bring something from home to make up a welfare package for the Shia volunteers on the front line outside Fallujah, each seven-year-old girl from Uruk elementary school donated a heartfelt gift: a bullet.

“I had mixed feelings when I opened the boxes that arrived from these little girls,” admitted Brigadier Sayeed Hamid al-Yasser, commander of a 2,600-strong group of volunteers that fight under the banner of Ansar al-Marjaeya. His troops had obeyed the fatwah of Grand Ayatollah Ali al-Sistani, Iraq’s top Shia cleric, flocking north to join the savage fight against Islamic State.