Hagia is an agri world located in the Sabbat Worlds. It is the birthplace of Saint Sabbat, and the location of her remains.
During the Sabbat Crusades the forces of Chaos attacked the world and mocked the people of the world by calling themselves Infardi which was the local word for "Pilgrim." Colonel-Commissar Ibram Gaunt and his regiment, the Tanith First and Only fought the Infardi in the capital city of the world, the Holy Doctrinopolis, and drove them out but at a very heavy cost. To redeem himself and his regiment, Gaunt led an honour guard to the Shrinehold of Saint Sabbat to safeguard the relics there from the incoming Chaos Fleet.