The massacre and capture of their compatriots outraged the Greeks in Thrace and Macedonia. They realized that Kaloyan was more hostile to them than the Latins. The burghers of Adrianople and Didymoteicho approached Henry of Flanders offering their submission. Henry ccepted the offer and assisted Theodore Branas in taking possession of the two towns. Kaloyan attacked Didymoteicho in June, but the crusaders forced him to lift the siege. Soon after Henry was crowned emperor of the Latins on 20 August, Kaloyan returned and destroyed Didymoteicho. He then laid siege to Adrianople, but Henry forced him to withdraw his troops from Thrace. Henry also broke into Bulgaria and released 20,000 prisoners in October. Boniface, King of Thessalonica, had meanwhile recaptured Serres.

Akropolites recorded that thereafter Kaloyan called himself "Romanslayer", with a clear reference to Basil II who had been known as the "Bulgarslayer" after his destruction of the First Bulgarian Empire.