The Battle of Sebastopolis is fought at Sebastopolis (mostly identified with Sebaste in Cilicia, but also with modern Sulusaray) in 692 between the Byzantine Empire and Umayyads under the caliphate of Abd al-Malik ibn Marwan.

The Battle ends the peace that had existed between the two powers since 680.The Umayyad army is led by Muhammad ibn Marwan, brother of the Caliph, and includes the minister of defense, the famously known Al-Hajjaj ibn Yusuf.

The Byzantines are led by Leontios and include a "special army" of 30,000 Slavs under their leader Neboulos.

The Umayyads, incensed at the breaking of the treaty, use copies of its texts in the place of a flag.

Though the battle seems to be tilting to the Byzantine advantage, the defection of upwards of 20,000 Slavs ensures a Byzantine defeat.

One source states that the Emperor Justinian II massacred the remaining Slavs, including women and children, at the Gulf of Nicomedia, yet modern scholars do not consider this a reliable account.