Taking advantage of the internal conflicts in the Byzantine Empire after Emperor Manuel's death, Béla III of Hungary reoccupied Croatia, Dalmatia and Syrmia, restoring Hungarian suzerainty over these territories after fourteen years.
Clashes and border conflicts between Hungary and the Byzantium lasted until 1167, when Stephen III had to renounce Dalmatia, Croatia and Syrmia to the Byzantine Empire.
The following period was characterized by internal struggles within the elite, while Manuel's daughter Maria Komnene (once engaged to Béla III) also contested her half-brother's right to the crown.
[10] Taking advantage of the internal conflicts in the Byzantine Empire, Béla III launched a campaign in the autumn of 1180 in order to restore the Hungarian suzerainty in Dalmatia.
[11] Ferenc Makk refused this standpoint, because the "Byzantium was not threatened by Venice in Dalmatia at the time", for instance, Doge Orio Mastropiero unsuccessfully attempted to regain Zadar from the Hungarians years later, in 1187.
In addition, Kilij Arslan II, the Seljuk Sultan of Rûm seized most of the southern coast of Asia Minor from the empire around the same time.
Historian Judit Gál considered after Béla recovered Dalmatia, Hungary's territories beyond the Drava were initially consolidated under a single ban after 1183.
[14] Simultaneously with Denis' appointment, Maurus Győr was installed as "governor of the whole coastal province" already by February 1181, when resided in Zadar and was involved in a verdict about some possession rights.
Andronikos Komnenos, marching to Constantinople with an army, accused Maria of Antioch, the mother and regent of the young Byzantine Emperor, Alexios II, of inciting Béla—her brother-in-law—to ravage the region of Belgrade and Barancs in May 1182, implying that Béla had by that time occupied Syrmia.
[18] During the campaign, the Hungarian king allied with the Serbs of Rascia and the Banate of Bosnia, who struggled for their independence and the usurpation of Andronikos Komnenos freed them from subordination to the Byzantine Empire under the leadership of Stefan Nemanja and Ban Kulin, respectively.
The two generals achieved limited successes along the defense line of the Balkan Mountains passes and plausibly forced the Hungarians to retreat till the river Sava.
[20] Some Hungarian historians – for instance, József Deér and Gyula Moravcsik – claimed that Béla III conducted the 1183 campaign in order to defend and support the interests of the late Manuel's family – Alexios II and Maria of Antioch – against the usurper Andronikos Komnenos.
Accordingly, the Hungarian monarch had no intention to expand his realm at the expense of the Byzantine Empire and Béla voluntarily retreat from the central Balkans after the execution of Maria.
There is a scholarly theory that Béla III had signed an armistice with Andronikos in that year, but Makk argued the temporary successes of Alexios Branas forced the Hungarians to sort out their queues due to increased losses and costs.
[22] The Norman invasion of the Byzantine Empire led by William II of Sicily took place around the same time, which made the internal political situation of the tyrannically ruling emperor Andronikos impossible.
[21] By the summer of 1185, Constantinople was itself threatened by the Norman invasion, which sparked a rebellion in the city, resulting the dethronement and lynching of Andronikos Komnenos in September.
[23] The new Byzantine emperor married Margaret in January 1186 at the latest, and Béla granted the region of Niš and Barancs to Isaac as his daughter's dowry.