structural:scholar_edition
Latin Wars

Although during the period of time from 1204 to 1261 the Bulgarians and the Byzantines mainly fought the Latins, both still held resentment towards each other. In spite of the initially welcome successes of the Bulgarians against the Latins, the Byzantine aristocracy now began to rebel or conspire against its rule. Kaloyan also changed course and turned mercilessly on his former allies, adopting the sobriquet Rōmaioktonos ("slayer of Romans"), as a counter-derivative from Basil II 's Boulgaroktonos ("slayer of Bulgarians"). Tsar Ivan Asen II (reign 1218 to 1241) tried to achieve the regency for the 11-year-old Latin Emperor, Baldwin II, after 1228, but the Latin aristocrats did not support Ivan Asen. He inflicted a crushing defeat on Theodore Komnenos Doukas of the Empire of Thessalonica, in the Battle of Klokotnitsa in 1230. Theodore's empire soon collapsed and Ivan Asen conquered large territories in Macedonia, Thessaly and Thrace. But generally the relations between the Bulgarians and Nicaea, the main Byzantine successor state, remained strong, as the new pro-Nicaean alignment of Bulgaria culminated with the marriage between Tsar Ivan Asen II's daughter Elena and the future Theodore II Laskaris, the son of Emperor John III Doukas Vatatzes of Nicaea. The dynastic union was celebrated in 1235 and coincided with the restoration of the Bulgarian patriarchate with the consent of the eastern patriarchs and with a siege of Constantinople by the combined forces of John III and Ivan Asen II. Later on, the Bulgarians decided to aid neither the Latin Empire nor the Nicaeans because both were too involved fighting each other to attack Bulgaria. During 1240s and 1250s the Emperors John III Doukas Vatatzes and his son Theodore II Laskaris led successful campaigns against the Tsardom.