Siege of Patras
805 CE.
Shown on the map at 38.250°, 21.733°.
The siege of Patras in 805 or 807 was undertaken by the local Slavic tribes of the Peloponnese, reportedly with aid from an Arab fleet. The siege's failure, attributed to the miraculous intervention of the city's patron, Saint Andrew, marked the consolidation of Byzantine control over the Peloponnese peninsula after two centuries of Slavic occupation over its western half. It also marked the beginning of the ascendancy of the Metropolis of Patras in the peninsula's ecclesiastical affairs.
Text from the Wikipedia article Siege of Patras (805 or 807), licensed CC BY-SA 4.0.