Militias have always been in Iraq, and they comprise an integral part of modern Iraqi history. They have been prevalent among both state authorities and their opponents. The very definition of Iraqi political parties, particularly after the republic was founded in 1958, is tied to the idea of military wings, assassin groups, secret security attachés and their resistors.

In other words, 2003 wasn't the year militias were discovered in Iraq. Before April of that year, the most recent iterations of Iraqi militia were the foreign combatants employed by the authorities under the name “mujahideen” to fight American forces. Those were preceded by “Saddam’s Guerrillas” and ultimately split into new, ambiguous militias as a result of the American presence in Iraq.

The idea of “resistance against the occupation” was hard to object to, but in many cases, it was little more than an excuse for new militias. The collapse of the state, the dissolution of its institutions, Iraq's opening to foreign forces and suspicions among different sects all provided natural motives to form militias, even after the withdrawal of the American army. Social upheaval, cultural turbulence and individual, regional and sectarian fear following 2003 not only contributed to the emergence of new militias; these factors also fostered a social environment with people who were sympathetic to militias, who needed them for protection, or who feared the militias so much that they kept their silence.

The announcement the Shiite Mahdi Army's formation coincided with similar announcements by a number of armed Sunni groups, including the Islamic Army and the 20th Revolutionary Battalion. It also coincided with the emergence of al-Qaeda in Iraq. These armed groups quickly reproduced and became more numerous, with their map growing increasingly complex. Until 2005, their slogan was “resisting the occupation” and “fighting its collaborators.” Most of them changed face between 2006 and 2007, and formed opposing sides in the civil war that has claimed the lives of thousands of Iraqis. Now the slogan has changed to “in defense of the sect.”