This article examines how landscape and environmental factors shaped the eleventh-century Norman conquest of southern Italy and Sicily. The conquest was documented in several narrative histories, including those of Amatus of Montecassino, William of Apulia, and Geoffrey Malaterra. These texts have been extensively analyzed for their rhetorical qualities as literary texts, but such an approach has tended to cast the landscape in a passive role, as an object awaiting rhetorical shaping. In light of recent developments in ecocritical studies, these texts ought to be revisited. The dynamic is not one of conquerors triumphing over conquered land. Instead, these texts offer a much more ambivalent picture. Norman mercenaries struggled to adapt to the ecological and environmental challenges of the region, its heat, volcanic activity, hostile fauna, and scarcity of water. A careful reading of these Latin historical accounts can be used to supplement absences in the archival record, and to provide a picture of medieval co-adaptation to the challenges of a particular Mediterranean landscape.