Battle of Sirmium

Part of the Komnenian restoration of the Byzantine Empire

Emperor Manuel I Komnenos

Date	July 8, 1167
Location	Sirmium, Byzantine Empire (now Serbia)
Result	Decisive Byzantine victory

Belligerents

Byzantine Empire

Kingdom of Hungary

Commanders and leaders

Andronikos Kontostephanos

Dénes, count of Bács

Strength

15,000 men

Casualties and losses

Unknown

800 captured
thousands killed

The Battle of Sirmium or Battle of Zemun (Hungarian: zimonyi csata) was fought on July 8, 1167 between the Byzantine Empire (also known as Eastern Roman Empire), and the Kingdom of Hungary. The Byzantines achieved a decisive victory, forcing the Hungarians to sue for peace on Byzantine terms.

From the mid 11th century, the Kingdom of Hungary had been expanding its territory and influence southwards, with a view to annexing the regions of Dalmatia and Croatia. This, and Hungarian alliances with the Serbian principalities, was the cause of tension with the Byzantine Empire, centred on Constantinople, which viewed Hungarian expansion as a potential threat to Byzantine dominance in the Balkans. The Byzantines and Hungarians launched a number of invasions of each other's territory, and the Byzantines regularly aided pretenders to the Hungarian throne. Friction and outbreaks of open warfare between the Byzantines and Hungarians reached a peak in the 1150s and 1160s.

The Byzantine emperor Manuel I Komnenos attempted to achieve a diplomatic and dynastic settlement with the Kingdom of Hungary. In 1163, under the terms of an existing peace treaty, King Stephen III's younger brother Béla was sent to Constantinople to be raised under the personal tutelage of the emperor himself. As Manuel’s relative (Manuel's mother was a Hungarian princess) and the fiancé of his daughter, Béla became a Despotes (a title newly created for him) and in 1165 he was named as an heir to the throne, taking the name Alexios. Since he was also the heir to the Hungarian throne, a union between the two states was a distinct possibility. But in 1167, King Stephen refused to give Manuel control of the former Byzantine territories allocated to Béla-Alexios as his appanage; this directly led to the war that ended with the Battle of Sirmium.

In 1167, bad health prevented Manuel from taking to the field in person, therefore he appointed his nephew Andronikos Kontostephanos, the Megas Doux, to the command of his field army, with orders to bring the Hungarian army to battle.

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