Rus'-Byzantine War (860)

Rus' Siege of Constantinople
Part of
The Rus' under the walls of Constantinople.
Date 860 Location Constantinople (Old East Slavic: Tsargrad, Old Norse: Miklagarðr) Result Successful Rus' raid on outskirts of Constantinople
Belligerents
Byzantine Empire	Rus'
Commanders and leaders
Michael III	Helgi of Holmgard, Rurik, Askold and Dir
Strength
unknown	~200 ships 5,000 men

The Siege of Constantinople of 860 was the only major military expedition of the Rus' Khaganate recorded in Byzantine and Western European sources. The cause of the siege was the construction of the fortress Sarkel by Byzantine engineers, restricting the Rus' trade route along the Don River in favor of the Khazars. Accounts vary regarding the events, with discrepancies between contemporary and later sources. 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. The event gave rise to a later Orthodox Christian tradition, which ascribed the deliverance of Constantinople to a miraculous intervention by the Theotokos.

The first mention of the Rus' near the Byzantine Empire comes from Life of St. George of Amastris, a hagiographic work whose dating is debated. The Byzantines had come into contact with the Rus' in 839. The exceptional timing of the attack suggests the Rus' had been informed of the city's weakness, demonstrating that the lines of trade and communication did not cease to exist in the 840s and 850s. Nevertheless, the threat from the Rus' in 860 came as a surprise; it was as sudden and unexpected "as a swarm of wasps", as Photius put it. The empire was struggling to repel the Abbasid advance in Asia Minor. In March 860, the garrison of the key fortress Loulon unexpectedly surrendered to the Arabs. In April or May, both sides exchanged captives, and the hostilities briefly ceased; however, in the beginning of June, Emperor Michael III left Constantinople for Asia Minor to invade the Abbasid Caliphate.

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