Peter II of Bulgaria

Taking advantage of the war between the Byzantine Empire and the Normans of Sicily, the rebels invaded Thrace and persuaded others to join them.[38] Heartened by the victories, Theodor-Peter "bound his head with a gold chaplet and fashioned scarlet buskins to put on his feet",[39] thus adopting insignia that had been used only by the emperors.[40] Although Choniates does not mention that Theodor-Peter also styled himself emperor, the use of imperial insignia shows that he either had been proclaimed emperor, or at least laid claim to the title.[41][42][43] Madgearu says, the coronation most probably took place before the end of 1185, because a priest, Basil, was allegedly made the head of the restored Bulgarian Orthodox Church in that year.[44]

Theodor-Peter laid siege to Preslav, which had been the capital of the First Bulgarian Empire, but they could not capture it.[45][46] The rebels again stormed into Thrace and carried away "many free [people], much cattle and draft animals, and sheep and goats in no small number" in early 1186.[39][47] To prevent the rebels from crossing the mountain passes, Isaac II launched a campaign against them, but they occupied "the rough ground and inaccessible places"[39] and resisted the attacks.[48] However, a sudden "blackness" (associated with the solar eclipse of 21 April 1186) rose up and "covered the mountains",[49] enabling the Byzantines to inflict a severe defeat on the rebels.[16][50]

Cumans depicted in the Radziwiłł Chronicle

After the Byzantine victory, a courtier stated that Theodor-Peter and Asen were soon forced to yield to the emperor, describing Theodor-Peter as a bull who had broken the yoke.[50] However, the brothers fled across the Lower Danube and sought assistance from the Cumans.[42][51] The imperial troops "set up fire to the crops gathered in heaps" by the local inhabitants, but made no major efforts to capture the rebels' fortresses which were "built on sheer cliffs and cloud-capped peaks".[42][52][53]

Isaac II also failed to garrison the castles along the Lower Danube, enabling the refugees to return, accompanied by Cuman troops in the autumn of 1186.[16][54] Theodor-Peter had promised rich booty and salary to the Cumans to talk them into supporting him, according to a letter that Niketas Choniates wrote on the emperor's name a year after the events.[55][56] The same author attributes the leading role to Asen in the ensuing military campaign in his chronicle.[55] The rebels and their Cuman allies invaded the Byzantine Empire and took control of Paristrion (or Moesia) between the Lower Danube and the mountains.[55][57] Thereafter the unification of Moesia and Bulgaria "into one empire as of old"[25] (namely, the restoration of the First Bulgarian Empire) became their principal goal.[58] Around that time (in 1187 or 1188), Asen became Theodor-Peter's co-ruler.[59][60]

According to a scholarly theory, Isaac II acknowledged the independence of the territories under the rule of Theodor-Peter and Asen in a peace treaty signed in the summer of 1188.[61][53] John Van Antwerp Fine writes, the brothers' realm "included the territory between the Balkan Mountains and the Danube".[53] Madgearu proposes, territories to the south of the mountains, as far as the line connecting Plovdiv, Stara Zagora and Ahtopol, were also incorporated into the new state.[61] The supposed treaty is not mentioned by Choniates.[61] Historian Paul Stephenson states that he has found no evidence in support of a treaty acknowledging the independence of the new state, but he also emphasizes that the territory to the north of the mountains was ruled by various Vlach, Bulgarian and Cuman lords who regarded Theodor-Peter and Asen as their sovereigns.[62]

Significant numbers of Bulgarians and Vlachs remained under Byzantine rule after 1188.[63] Those who were subjected to the Byzantine governor of Braničevo harassed the crusaders of the Holy Roman Emperor, Frederick Barbarossa, in July 1189.[63] Around that time, Stefan Nemanja, Grand Župan (or ruler) of Serbia, seized parts of the Byzantine theme (or district) of Bulgaria.[64] Nemanja and Theodor-Peter concluded an agreement against the Byzantines.[63]

Theodor-Peter wanted to take advantage of the crusaders' presence to expand his rule.[65] He and his brother took control of "the region where the Danube flows into the sea"[66] (present-day Dobruja) in the summer. He had already dispatched an embassy to Barbarosa in Niš in July,[67] offering him "due respect and a promise of faithful assistance against his enemies".[66][68] He sent a second envoy to Barbarossa, who had come into conflict with Isaac II, to Adrianople (now Edirne in Turkey) in December, offering "forty thousand Vlachs and Cumans armed with bows and arrows"[69] to fight against the Byzantines.[70][71] He also announced his claim to "the imperial crown of the kingdom of the Greeks"[69] (or the Byzantine Empire).[70]

Barbarossa was indeed contemplating an attack against Constantinople, but he changed his mind and concluded a peace treaty with Isaac II in February 1190.[72][73] On the day when the treaty was concluded, Isaac II's envoy tried to talk Barbarossa into a joint military action against the Vlachs, while Theodor-Peter's delegate again proposed an alliance against the Byzantines.[74] However, Barbarossa, who wanted to continue the crusade towards the Holy Land, refused both offers.[74]

Second Bulgarian Empire from 1185 to 1196 under the rule of Tsar Peter IV and Tsar Ivan Asen I., according to a Bulgarian historical atlas. The theory that Bulgaria included Oltenia and Muntenia, as it is presented on the map, is not universally accepted by historians.[75]

After Barbarossa left Thrace, Isaac II was able to make new attempts to recover the lands lost to Theodor-Peter and Asen.[76] In July 1190, he invaded the brothers' realms across the Rish Pass and dispatched a fleet to the Lower Danube to prevent the Cumans from crossing the river.[77] However, the brothers had already strengthened their fortification and avoided direct confrontations with the invaders.[76] The emperor decided to return to his capital after he was informed that Cuman troops had crossed the Lower Danube in September.[78] The Vlachs and the Bulgarians ambushed the imperial army at a narrow pass and inflicted a major defeat on it.[8] Isaac II escaped, but much of the army perished and the victors seized "the more valuable of the emperor's insignia",[79] including his pyramidal crown and relics associated with the Virgin Mary.[80]

The Vlachs, Bulgarians and Cumans resumed their raids against Byzantine territories.[80] They sacked Varna and Pomorie; they destroyed Triaditsa and seized the relics of Ivan of Rila, a saint especially venerated by the Bulgarians.[8][81] Isaac II routed Cuman marauders near Plovdiv in April 1191.[82] He made his cousin, Constantine Doukas Angelos, the commander of Plovdiv in 1192.[82][83] Constantine prevented Theodor-Peter and Asen from making frequent pillaging raids against Thrace, but he was blinded after he tried to dethrone the emperor.[83][84] Theodor-Peter and Asen rejoiced over Constantine's fate. According to Choniates,[84] they said they were ready to make "Isaac emperor over their own nation, for he could not have benefited the Vlachs more than gouging out Constantine's eyes".[85]

At least two eulogies delivered in 1193 provide evidence that Isaac had succeeded in creating a rift between Theodor-Peter and Asen.[86][87] An orator mentioned that Theodor-Peter had concluded a peace treaty with the Byzantines; the other described him as "a stumbling block to his brother" and an enemy to his own family, while describing Asen as a "most reckless and obdurate rebel".[87] George Akropolites records that Preslav, Provadia and the "area around them" was still known as "Peter's land"[88] in the 13th century.[89] The sources suggest that the brothers divided the territories under their rule into two, most probably in 1192, according to Madgearu.[89] Receiving the northeastern region, Theodor-Peter set up his capital at Preslav.[89] Fine says the strife between the brothers was most probably soon rectified, because they jointly ordered the invasion of Thrace in 1193.[90]

Asen was murdered in Tarnovo by the boyar Ivanko in the fall of 1196.[91] Theodor-Peter soon mustered his troops, hurried to the town and laid siege to it.[92][93] Ivanko sent an envoy to Constantinople, urging the new Byzantine Emperor, Alexios III Angelos, to send reinforcements to him.[91] The emperor dispatched Manuel Kamytzes to lead an army to Tarnovo, but fear of an ambush at the mountain passes led to an outbreak of mutiny and the troops forced him to return.[94] Ivanko realized that he could not defend Tarnovo any more and fled from the town to Constantinople.[92] Theodor-Peter entered Tarnovo.[92] After making his younger brother Kaloyan the ruler of the town, he returned to Preslav.[92][95]

Theodor-Peter was murdered "in obscure circumstances"[93] in 1197. He was "run through by the sword of one of his countrymen",[96] according to Choniates' record.[97] Historian István Vásáry writes, Theodor-Peter was killed during a riot;[93] Stephenson proposes, the native lords got rid of him, because of his close alliance with the Cumans.[97]