The Ring of Iron is the name given to the massive complex of orbital shipyards, refineries and construction facilities that encircle the equator of the Adeptus Mechanicus' homeworld of Mars in the Sol System. The exploratory and expeditionary fleets of the Emperor of Mankind's Great Crusade were constructed in the orbital shipyards of the Ring of Iron during the late 30th and early 31st Millenniums. During the Horus Heresy, the Dark Mechanicus struck against the Ring of Iron and damaged large portions of its facilties. The terrible destruction could be seen from the surface of Mars as a blazing fire in the sky. After the end of the Heresy and the reestablishment of Imperial rule over Mars, the Ring of Iron was repaired and put to work once more churning out the starships of the newborn Imp