The Rus'-Byzantine War of 860 is 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, when the empire was occupied by the ongoing Byzantine-Arab Wars and unable to deal with the Rus' threat.

After pillaging the suburbs of the imperial capital, the Rus' retreat, although the nature of this withdrawal, and indeed which side had been victorious, is subject to debate.

This event gives rise to a later Orthodox Christian tradition, which ascribes the deliverance of Constantinople to a miraculous intervention by the Theotokos.