The Rus'–Byzantine War of 860 was the only major military expedition of the Rus' Khaganate recorded in Byzantine and Western European sources. Accounts vary regarding the events that took place, with discrepancies between contemporary and later sources, and the exact outcome is unknown. It is known from Byzantine sources that the Rus' caught Constantinople unprepared, while the empire was preoccupied by the ongoing Byzantine-Arab Wars and unable to deal with the Rus' threat. After pillaging the suburbs of the Byzantine capital, the Rus' retreated, although the nature of this withdrawal, and indeed which side was victorious, is subject to debate. This event gave rise to a later Orthodox Christian tradition, which ascribed the deliverance of Constantinople to a miraculous intervention by the