Battle of Sirmium The Battle of Sirmium or Battle of Zemun ( ) 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 " Hetaireia i " , 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 taxiarch ies 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 żupa n 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 .