Definition: "Mahdi" is Arabic for "the guided one." The Mahdi Army was founded in August 2003 by Iraqi Shiite militant Islamist leader Muqtada al-Sadr , ostensibly to give poor Shiites protection from criminals, Sunnis and coalition occupation forces. The Mahdi Army, however, itself a collection of thugs, gang members and undisciplined militants, terrorized civilians, played a large role in sectarian executions targeting Sunnis, and attacked coalition forces as well as Iraqi government or police installations.
The Mahdi Army was mostly responsible for British troop deaths in Basra, Iraq's second-largest city and a Shiite stronghold in the south of the country.