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How did Norman conquests in Italy weaken the Byzantine Empire?
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Byzantine Empire
The Virgin Mary holding the Christ Child (centre), Justinian (left) holding a model of the Hagia Sophia, and Constantine (right) holding a model of the city of Constantinople; mosaic from the Hagia Sophia, 9th century.
The Norman conquests in Italy significantly weakened the Byzantine Empire by dismantling its territorial presence in the West and contributing to a broader decline in its military and economic power during the 11th century.12
The impact of the Norman expansion included:
- Loss of Territory: Beginning as mercenaries, the Normans—led by figures such as the House of Hauteville—methodically seized Byzantine-controlled lands in southern Italy. This process culminated in the fall of Bari in 1071, which marked the end of Byzantine rule in Italy and extinguished hopes for the reconquest of Sicily.31
- Strategic and Symbolic Decline: The loss of Italy, occurring in the same year as the disastrous Battle of Manzikert against the Seljuq Turks, illustrated the empire's inability to defend its frontiers on two fronts. This territorial retreat underscored a permanent political and cultural division between the Greek East and the Latin West, further solidified by the East-West Schism of 1054.1
- Military Pressure: The Normans continued to threaten the empire even after their Italian conquests, eventually launching direct attacks on Byzantine territory in the late 11th century.3