The Battle near Constantinople

After an unsuccessful attempt to capture Constantinople, Simeon tried several more times. One attempt came in 921. His troops reached Manglava and Katasyrtai, towns near Constantinople. In response, the emperor also sent troops from the imperial guard. The battle took place near Kasımpaşa on the seashore.

The Byzantines suffered heavy casualties, and the Bulgarians achieved a major victory. Tsar Simeon concluded a secret treaty with the Egyptian caliph al-Mahdi, seeking an alliance to capture Constantinople.