Battle of Sirmium

The Battle of Sirmium or Battle of Zemun (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.

Background
During the 1150s and 1160s, the Kingdom of Hungary had been expanding its territory and influence, with a view to annexing the region around Dalmatia and Croatia. This was the cause of some tension with the Byzantine Empire, centred on Constantinople, which viewed Hungarian expansion as a potential threat to Byzantine dominance in the Balkans. The Byzantine emperors launched invasions against the Kingdom of Hungary and regularly aided pretenders for the throne.

Manuel I Komnenos also found a diplomatic, dynastic way to bind the Kingdom of Hungary to the empire. 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 an 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.

Battle
During the early summer of 1167, the Byzantine army under Andronikos Kontostephanos managed to lure a combined Hungarian force to battle near Sirmium. According to Byzantine historian John Kinnamos (who refers to the Byzantines as Romans, in deference to their status as the political continuators of the Eastern Roman Empire), the disposition of the two opposing armies was thus:



The Byzantine army was composed of one-third foreign and two-thirds native units. It was arrayed in three divisions, as was the usual practice, at some distance from the river Sava, which was to the rear. The main battle line was shielded by a screen of horse archers – Turks and Cumans – and some western mercenary knights, who had made up the vanguard of the army. The centre, which had constituted the rearguard on the march, was commanded by Kontostephanos himself, and consisted of the imperial guards units, including the Varangians and Hetaireiai, units of Italian mercenaries from Lombardy (probably lancers) and a unit of 500 armored Serbian allied infantry, as well as the Vlach cavalry. The left wing, which had been the second division on the march, was composed of regular Byzantine and allied units arrayed in four taxiarchies or 'brigades' under Demetrios and George Branas, Tatikios Aspietes and Kogh Vasil. On the right – the third division on the march – were placed the elite Byzantine units and German mercenaries, together with some Turkish units. This division was commanded by the chartoularios Andronikos Lampardas and, probably, John Kontostephanos the brother of the megas doux. Behind each wing division, and following standard Byzantine practice, were placed units to cover the Byzantine flanks or to outflank the enemy and take him in the rear should the opportunity arise; and behind the centre was drawn up the reserve, three taxiarchies of infantry and archers, with a number of heavily armoured Turks, probably infantry also.

The Hungarian commander, Dénes, count of Bács (called Dionysios in Byzantine sources), drew his army up in three divisions in a single broad battle line. Although the Byzantine sources say that he mixed infantry and cavalry without distinction, this most probably reflects a battle order with infantry drawn up in the centre and behind the cavalry, upon which the Hungarians clearly relied for the effectiveness of their attack. Choniates describes the Hungarian army as being composed of knights, archers and light infantry. Contemporary Hungarian armies often lacked infantry and Byzantine sources possibly referred to servants and other camp followers as infantry. The soldiers of the front rank of the Hungarian cavalry are described as being heavily armoured, and mounted on armoured horses.

The battle commenced with the Byzantine light-armed troops skirmishing forward to harry the opposing lines with arrows and persuade them to mount a charge, before which they were to retire. This was successful, and the whole Hungarian line surged forward. The Byzantine left wing, with the exception of the brigades led by Kogh Vasil and Tatikios, was immediately pushed back and broke, possibly in feigned flight, towards the river, where it quickly reformed. In the centre and on the Byzantine right, the Hungarian charge was held. The Byzantine right then counter-charged, and at the same time the regrouped Byzantine left-wing units also re-entered the conflict, attacking the Hungarians who were pinned by the two taxiarchies which had not withdrawn. Andronikos Lampardas then led an attack on the troops around the Hungarian commander and brought them to a halt; a deadly melee ensued with the Byzantine heavy cavalry resorting to the use of their fearsome iron maces. The battle had reached a decisive point. Kontostephanos, recognising the crisis of the battle, now deployed his remaining reserves. He counter-attacked in the centre and ordered forward the infantry along the whole front, driving the Hungarian forces back. The enemy divisions then began to break up in disorder and the whole Hungarian army turned to flight. The Byzantines captured the main Hungarian standard, which was mounted on an oxen-drawn wagon similar to the Italian carroccio. Count Dénes's warhorse was also taken, though the Hungarian commander managed to escape. Many of the fleeing Hungarians were killed or captured by a Byzantine flotilla operating in the river that they needed to cross to get to safety. Five senior Hungarian commanders with the title żupan were captured, along with 800 other soldiers. Over two thousand armours were taken from the dead and countless helmets, shields and swords. The following day the Byzantine army plundered their enemy's abandoned encampment.

Aftermath
The Hungarians sued for peace on Byzantine terms and recognised the empire’s control over Bosnia, Dalmatia, Croatia south of the Krka River as well as the Fruška Gora. They also agreed to provide hostages for good behaviour; to pay Byzantium a tribute and supply troops when requested. The Battle of Sirmium completed Manuel's drive to secure his northern frontier.

When Manuel's own son was born, Béla was deprived of the title despot and his position as heir to the imperial throne. In 1172, Stephen III died and Béla, with the help of Emperor Manuel, seized the throne of the Kingdom of Hungary. Béla had to swear that he would never harm Manuel and he remained loyal to the Empire until Manuel's death, but then he conquered lands previously held by the Byzantines.