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For Isaac Angelus even a temporary interruption of hostilities against the Normans was of very great advantage, for in the first years of his reign events of great importance to the Empire had taken place in the Balkan peninsula. Bulgaria, which had been conquered by Basil II Bulgaroctonus in 1018, after several unsuccessful attempts to regain her independence finally
threw off the Byzantine yoke and in 1186 established the so-called Second Bulgarian Kingdom.At the head of this movement stood two brothers, Peter or Kalopeter and Asen (Asan). The question of their origin and of the participation of the Wallachian element in the insurrection of 1186 has been several times discussed, and formerly historians believed that the brothers had grown up among the Wallachs and had adopted their tongue. In the persons of the leaders, said V. Vasilievsky, there was embodied exactly that fusion into one unit of the two nationalities, Bulgarian and Wallachian, that has been obvious in all narratives of the struggle for freedom and has been emphasized by modern historians. More recently, Bulgarian historians have traced the origin of Peter and Asen to the Cuman-Bulgarian racial elements in northern Bulgaria, denied the strength of the Wallachian-Roumanian element in the insurrection of 1186, and considered the foundation of the Second Bulgarian Kingdom of Trnovo a national Bulgarian achievement. Modern Roumanian historians, however, vigorously emphasize again the importance of the part played by the Wallachians in the formation of the Second Bulgarian Kingdom and say that the dynasty of the new kingdom was of Wallachian, i.e. Roumanian, origin.
Some elements of Bulgarian and Roumanian nationalism have become involved in this question, so that it is necessary to reconsider it with all possible scholarly detachment and disinterestedness. On the basis of reliable evidence, the conclusion is that the liberating movement of the second half of the twelfth century in the Balkans was originated and vigorously prosecuted by the Wallachians, ancestors of the Roumanians of today; it was joined by the Bulgarians, and to some extent by the Cumans from beyond the Danube. The Wallachian participation in this important event cannot be disregarded.
The best contemporary Greek source, Nicetas Choniates, clearly stated that the insurrection was begun by the Vlachs (Blachi); that their leaders, Peter and Asen (Asan), belonged to the same race; that the second campaign of the Byzantine Empire during this period was waged against the Vlachs; and that after the death of Peter and Asen the Empire of the Vlachs passed to their younger brother John. Whenever Nicetas mentioned the Bulgarians, he gave their name jointly with that of the Vlachs: Bulgarians and Vlachs. The western cleric Ansbert, who followed the Emperor Frederick Barbarossa in his crusade (1189-1190), narrated that in the Balkans the Emperor had to fight against Greeks and Vlachs, and calls Peter or Kalopeter Emperor of the Vlachs and of the most part of the Bulgarians (Blacorum et maxime partis Bulgarorum dominus) or imperator of the Vlachs and Cumans, or simply Emperor of the Vlachs who was called by them the Emperor of Greece (Kalopetrus Bachorum (Blachorum) dominus itemque a suis dictus imperator Grecie). Finally, Pope Innocent III in his letters to the Bulgarian King John (Calojoannes) in 1204 addressed him as King of Bulgarians and Vlachs (Bulgarorum et Blacorum rex); in answering the pope, John calls himself imperator omnium Bulgarorum et Blacorum, but signs himself imperator Bulgariae Calojoannes; the archbishop of Trnovo calls himself totius Bulgariae et Blaciae Primas.Although the Wallachians initiated the movement of liberation, the Bulgarians without doubt took an active part in it with them, and probably contributed largely to the internal organization of the new kingdom. The Cumans also shared in the movement. The new Bulgarian kingdom was ethnologically a Wallachian-Bulgarian-Cuman state, its dynasty, if the assertion of Nicetas Choniates is accepted, being Wallachian. The cause of the revolt was the discontent with the Byzantine sway felt by both Wallachians and Bulgarians, and their desire for independence. The time seemed particularly auspicious to them, since the Empire, which was still enduring the consequences of the troubles of Andronicus' time and the revolution of 1185, was unable to take adequate measures to put down the revolt. Nicetas Choniates naively said that the revolt was caused by the driving away of the Wallachs cattle for the festivities held on the occasion of the marriage of Isaac Angelus to a daughter of the king of Hungary.
Peter, this renegade and evil slave, as he was called by the metropolitan of Athens, Michael Acominatus, and Asen at first received some defeats from the Byzantine troops; but they were able to enlist the aid of the Cumans, who lived beyond the Danube. The struggle grew more difficult for the Empire, and Peter and Asen succeeded in concluding a sort of treaty.
Peter had already assumed the title of tsar at the outset of the revolt and had begun to wear the imperial robes. Now the new Bulgarian state was recognized as politically independent of Byzantium, with a capital at Trnovo and an independent national church. The new kingdom was known as the Bulgarian Kingdom of Trnovo, Simultaneously with the Bulgarian insurrection a similar movement arose in Serbian territory, where the founder of the dynasty of Nemanya, the Great Zupan (Great Ruler) Stephen Nemanja, who laid the foundation for the unification of Serbia, made an alliance with Peter of Bulgaria for the common fight against the Empire.
In 1189, as a participant in the Third Crusade, Frederick Barbarossa of Germany was passing across the Balkan peninsula towards Constantinople on his way to the Holy Land. The Serbs and Bulgarians intended to use that favorable opportunity and to obtain their aim with Frederick's help. During his stay at Nish Frederick received Serbian envoys and the Great Zupan Stephen Nemanya himself, and at the same time opened negotiations with the Bulgarians. The Serbs and Bulgarians proposed to Frederick an alliance against the Byzantine Emperor, but on condition that Frederick should allow Serbia to annex Dalmatia and retain the regions which had been taken away from Byzantium, as well as that he should leave the Asens in permanent possession of Bulgaria and secure the imperial title to Peter. Frederick gave them no decisive reply and continued his march. In this connection a historian of the nineteenth century, V. Vasilievsky, remarked: There was a moment when the solution of the Slavonic problem in the Balkan peninsula was in the hands of the western Emperor; there was a moment when Barbarossa was about to accept the help of the Serbian and Bulgarian leaders against Byzantium, which undoubtedly would have led to the ruin of the Greek Empire.
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