The Serbian revolt broke out in 1149 with raids on Byzantine territory, encouraged by Norman Sicily and Hungary. Serbia had entered an alliance with Hungary that could offer Serbian ruler Uroš II support in his fight for independence against the powerful Byzantine Empire. The Serbian revolt had come as a shock, and it exposed Byzantine weaknesses in the control of the Balkans and in diplomacy. Byzantine emperor Manuel I Komnenos diverted his attention from southern Italy to deal with the Serbs, and conquered fortresses in the Raška region in southwestern Serbia, but was unable to capture Uroš II. Although successful, the 1149 campaign did not give the expected results as Serbia endured the destruction. In 1150, the Serbian army located in the Tara River Canyon received a Hungarian supportive unit, while Manuel had mustered an army in Niš. A battle was fought at the Tara river between a Serbian–Hungarian force and the Byzantine army of Manuel, which included prominent generals. Manuel had marched with "little preparation, as he deemed them unworthy opponents in battle", but the Serbs put up a much stiffer resistance than expected and boldly met the Byzantine army in battle. After a string of fights between smaller number of troops, ambushes and duels, the Byzantines were victorious, and Uroš II pledged loyalty.
Background
In the two decades following the Byzantine–Hungarian War (1127–1129), in which Serbs had revolted, Byzantine relations with its Serbian vassals and Hungary were positive. In this period, Serbia and Hungary entered firm relations through dynastic marriage. In 1129–1130, the heir of Stephen II ( 1116–1131), Hungarian prince Béla II, married Jelena, the daughter of Serbian ruler Uroš I ( 1112–1145), but this seems to not have bothered Byzantine interests. Uroš's son (Jelena's brother) Beloš also joined the Hungarian court, and both Jelena and Beloš became very influential., This Hungarian–Serbian alliance could offer Uroš support in his fight for independence against the ever more powerful empire that managed to quell any previous uprising. The Komnenian army had shown its effectiveness in the Balkans, and the alliance would be a counter-measure to this. The fight for Serb independence was carried in the Serbian hinterland (also called Raška/Rascia in historiography), as the other Serb polity in the maritime, Zeta (Duklja), was unable to offer support as it had been worn out from rebellion and internal conflict. In 1137, Bosnia became a subject of Hungary, possibly as part of an agreement between Béla II ( 1131–1141) and Uroš I. In 1141, Géza II, the son of Béla II and Jelena, succeeded the Hungarian throne, and at this time, Beloš was the most powerful in the Hungarian court. In 1143, Manuel I Komnenos succeeded the Byzantine throne, and he inherited a strong and rising empire which had been mostly disengaged in the East to focus on Europe. Serbia was thus pressured, while Manuel sought to preserve the status quo in Hungary. The Serbian throne was succeeded by Uroš's son Uroš II. In 1146, Serbian military assistance was sent by Uroš II for Manuel's expedition against Seljuk sultan Mesud I.
In 1147, relations between European states were affected by the decision for a new Catholic Crusade, where German and French crusader armies would cross Byzantine territory in the Balkans (Belgrade–Braničevo–Niš–Serdica) and further into Asia Minor. Manuel entered an alliance with Conrad III of Germany, while Louis VII of France was allied with Siculo-Norman Roger II of Sicily. Roger II had Corfu taken from the Byzantines and started a war in autumn 1147. By 1148, the political situation in the Balkans was divided into the alliance of Byzantium and Venice, and that between the Siculo-Normans and Hungary. The Serbs, Hungarians and Normans exchanged envoys because it was in Siculo-Norman interest to stop Manuel's plans to recapture Italy. A Serbian revolt would need more fighting power and a wider battlefield, and thus, for the first time in history, Serbia joined a European anti-Byzantine alliance.
The events of the Serbian revolt and Manuel's campaigns are known from Theodore Prodromos (1100–1165), Michael of Thessaloniki ( 1149–1156), John Kinnamos (1143–1185), and Niketas Choniates (1155–1217). Kinnamos is the most detailed account, although he tends to exaggerate.
1149 campaign In 1149, the Serbians raided Byzantine territory, encouraged by Roger II of Norman Sicily, while Byzantine emperor Manuel I Komnenos was preoccupied with the Siege of Corfu. It is unknown which frontier provinces Uroš II attacked, as contemporaries do not name them. The Serbs posed a danger in case of a Byzantine attack on Italy, as they could strike at the Byzantine Adriatic bases. Another brother of Uroš II and Beloš, Desa, had by 1149 come to rule Travunia, Upper Zeta, and likely Zahumlje., Some historians (such as F. Šišić, Fine Jr., T. Živković) put Desa's takeover of Travunia and Duklja, the latter held by loyal Byzantine vassal Radoslav, in connection with the 1149 revolt (as mentioned in the Chronicle of the Priest of Duklja, )., The LPD describes how Radoslav was pushed to his southwestern holdings in Kotor, and retained only that coastal area, while the brothers Desa and Uroš II held much of inland Duklja and Travunia, i.e. over two thirds of what had been Duklja, and that Radoslav sought help from the emperor, who sent aid from Durazzo. T. Živković dated Desa's takeover of Travunia and Zeta to before the end of Uroš I's reign (1144/1145) and believed Uroš II's anti-Byzantine politics began with this, supported also by Beloš in Hungary, and that the provinces that were attacked in 1149 included Duklja, intruded by Desa.
After retaking Corfu in the summer of 1149, emperor Manuel divided his army into two, with one left with megas domestikos John Axouch at Avlona to cross into Italy and use Ancona as a base of operations, while he took the other part to the Balkans, having learnt of an uprising by the Serbs in Raška. According to Choniates, Manuel learnt of the revolt while at Avlona, from where he left for Pelagonia where he planned the campaign. The Serbian revolt had come as a shock, and it exposed Byzantine weaknesses in the control of the Balkans and in diplomacy. Judging by Manuel's swift and strong retaliation, leaving the campaign against Roger II, the Serbian revolt must have been of wider proportion and successful. The Serbs were not aided by any foreign power in 1149, perhaps due to Manuel's quick handling.
Manuel's campaign went in the Pelagonia–Skopje–Kosovo line. From Pelagonia, Manuel marched north, via the Kosovo field to Ras, which he quickly took, archaeological evidence showing that the western ramparts of the Ras fortress were destroyed in the Byzantine assault. There, he left sebastohypertatos Constantine Angelos with a strong garrison, while he continued the campaign., Manuel advanced further into the Nikava province (located either in the Upper Ibar, or in the Pešter–Sjenica area or towards Nova Varoš), part of Uroš II's crown land, and easily conquered the fortresses along the way. He took the well-defended Galič after three days and an assault, and took captives, including soldiers and shepherds, which were settled in Serdica and other parts of the empire. It is believed that the Serbs had rebuilt the Galič fortress by this time. The campaign had the mission to completely cut off the southern provinces of Uroš II and to secure the hinterland for the Byzantine army in continued warfare. While at Galič, Manuel received news that Uroš II clashed with Angelos at Ras. Uroš II attacked individual Byzantine detachments. Manuel set out, while Uroš II declined open pitched battle, using the harsh geography and withdrawing to the hinterland in the west or north-west. The estates of Uroš II were burnt down by Manuel. Manuel I's army was however unable to pursue the Serbs into the mountains, nor to capture Uroš II,, and returned home to try again the next year. Michael of Thessaloniki mentioned how Manuel had attacked the centre of the Serbian land. After the defeat in 1149, Uroš II went west of the Lim river and planned for war against the Byzantines. Although successful, the 1149 campaign did not give the expected results as Serbia endured the destruction. According to Choniates, Manuel informed Constantinople of his success via megas domestikos John Axouch; Kinnamos does not mention Axouch as participating in the 1149 campaign, while his activities in other places is well-known.
1150 campaign
Manuel's campaign was not finished in 1149, as seen in the coming, much larger incursion again personally led by Manuel against Uroš II in 1150. According to Choniates, Uroš II behaved "worse than before", meaning he organized war against Byzantium. Manuel mustered a large army in Niš, which included the most prominent military commanders such as protosebastos John Komnenos, John Doukas Kamateros, John Kantakouzenos, Michael Branas and Giphardos,, which commenced at the end of the summer of 1150, "when the roads to Serbia become more suitable for the army"., Armed conflict likely began in late September or early October. The Byzantines learnt that the Serbian army awaited military aid from Hungary. Manuel heard of this while at Niš, and decided to send a detachment across the Lugomir župa (opposite Ćuprija) to the Sava river to clash with this force, stopping it from joining the Serbian army., Up until this, Hungary was not a factor for Manuel in this campaign in Serbia. The Hungarian supportive unit most likely descended by the Drina which was the Serbian–Bosnian natural border, and not central Serbia which was militarily in firm Byzantine control; the Byzantine detachment that arrived at the Sava thus changed course to the Drina. The detachment clashed with the Hungarian unit "while procuring food for the cattle", likely while camped by the road which the Hungarian unit travelled on, and Manuel, still at Niš, then sent another detachment under his nephew, protosebastos John Komnenos, when he heard of the clash., This Hungarian unit was defeated by John before it could join the Serbs, and was pursued to the Strymon river where it lost many men, and was then pursued towards the Tara, until the Byzantine force decided to return to Manuel's army. At this time, the Serbian army likely was situated between the Lim and Tara, closer to Tara. Uroš II had made extensive planning, mustering well-armed Serbs and župans (counts).
Manuel camped half-way on the road to Sečenica (Sočanica on the Ibar river), likely somewhere near Kuršumlija, and was still unaware of the location of the Serbian army. From Serbian captives, he learnt that the Hungarian aid had not yet joined the Serbian army, and thus led the Byzantine army onward. The likely route was across the Ibar bridge at the Sočanica confluence, into Rogozna, Ras, Sjenica, towards Bijelo Polje and from there on the Bijelo Polje–Mojkovac road which was the most convenient. Arriving at the Tara river, in the early morning, the Byzantines had sent scouts to attract the Serbs out of the mountain and shoot them with archers, however, the scouts returned in fear, seeing an "innumerable army". The Serbian army was supported by Hungarian cavalry that included non-Christian Khalisioi (who stayed at Syrmia). The Byzantines had failed to prevent the Hungarian supportive unit from joining the Serbian army.