After Mosul fell to the Islamic State (IS) on June 10, 2014, and the latter continued its advance toward Baghdad, Iraq’s Shiite Grand Ayatollah Ali al-Sistani issued a statement June 13, calling on all Iraqis to join the front in support of the Iraqi armed forces.
As a result, volunteers were organized into military units that later became known as the Popular Mobilization Units, which included a number of religious seminary students and teachers from Najaf, who joined the fight wearing their religious garb.