Isaac II Angelos
The rebellion failed to immediately capture Bulgaria's historic capital Preslav, but established a new capital city at Tărnovo, presumably the center of the revolt. In 1186 the rebels suffered a defeat, but Isaac II Angelos failed to exploit his victory and returned to Constantinople. With the help of the chiefly Cuman population north of the Danube, Peter IV and Ivan Asen recovered their positions and raided into Thrace. When Isaac II Angelos penetrated into Moesia again in 1187 he failed to capture either Tărnovo or Loveč, and he signed a treaty effectively recognizing the Second Bulgarian Empire, but neither side had any intention of keeping the peace. When the Third Crusade led by Frederick I, the Holy Roman Emperor, was advancing towards Constantinople, representatives of Peter IV and Ivan Asen approached him with offers of military assistance against the latently hostile Isaac II Angelos at Niš and again at Adrianople.