On March 24, 1201, Tsar Kaloyan captures Varna from the Byzantines. In 1201, Bulgaria, under the rule of Tsar Kaloyan, was on the rise. At that time, the strong fortress of Varna was a possession of Byzantium. It was in an important strategic location and posed a threat to the Bulgarian state. The fortress was protected by the sea on one side and by a moat on the other three sides.
Tsar Kaloyan besieged Varna from 3 sides. The garrison put up strong resistance. Then the Bulgarians built a high siege tower as high as the walls and turned it into a moat. Thus it was fixed on the wall of the fortress and the Bulgarians invaded the fortress using it, capturing it in 3 days.
Kaloyan ordered the captured Romans to be thrown into a ditch and buried alive with earth. Georgi Akropolite writes: “He was thus avenging, as he says, the evils that Emperor Basil had committed against the Bulgarians. And when he said that Basil called himself the Bulgar-slayer, he called himself the Romeo-slayer“.
The Byzantine historian Nikitas Choniates wrote about the siege of Varna: “Without being afraid of the sanctity of the day (it was Easter) and without being ashamed of the name of Christ, which he (i.e. Tsar Kaloyan) pronounced only with his mouth, prompted by bloodthirsty demons, he pushed into the ditch all those he had captured alive, and threw dirt until he filled the ditch. Thus the place became a common grave. After destroying the fortress walls, he returned to Moesia, celebrating the day with such sacrifices and bloody commemorations.“ At the end of 1201, peace negotiations began between Bulgaria and Byzantium. Peace was concluded at the beginning of 1202.