Byzantine–Norman wars
Wars between the Normans and the Byzantine Empire were fought from 1040 until 1185, when the last Norman invasion of the Byzantine Empire was defeated. At the end of the conflict, neither the Normans nor the Byzantines could boast much power as by the mid-13th century, exhaustive fighting with other powers had weakened both, leading to the Byzantines losing Asia Minor to the Ottoman Empire in the 14th century, and the Normans losing Sicily to the Hohenstaufen.