Kaloyan's troops pillaged Thrace and Macedonia after his victory over the Latins. He launched a campaign against the Kingdom of Thessalonica, laying siege to Serres in late May. He promised free passage to the defenders, but after their surrender he broke his word and took them captive. He continued the campaign and seized Veria and Moglena (now Almopia in Greece). Most inhabitants of Veria were murdered or captured on his orders. Henry (who still ruled the Latin Empire as regent) launched a counter-invasion against Bulgaria in June. He could not capture Adrianople and a sudden flood forced him to lift the siege of Didymoteicho.