This is the battle of Aheloy which happened in 917. That is the greatest early medieval battle in European history. In the fight take part about 120 thousand people. The Byzantines fight against the Bulgarians. At that time Byzantium is in peace with all its enemies and brings its most elite army and allies into this battle in order to end Bulgaria's rule in the Balkans. The battle is difficult for both sides. Tsar Simeon tactically hides behind a hill with 2 thousand horsemen waiting for the perfect moment to enter the battle. When he attacks, his white horse is killed and he falls on the ground. His soldiers see their tsar has fallen and they start fighting like never before. As a result the Bulgarians crush the Byzantine army and push it back to the Aheloy river where they kill everyone. According to the chronicles, the elite of the Byzantine army is killed in this battle. Mountains of bones remain there for centuries.

Byzantine people were from different nationalities and most of their emperors were Syrians and Armenians. Tsar Simeon did not want to conquer the empire because he realized this would destroy it. He wanted to be chosen by the people so he can keep Byzantium the way it was. That is why he never captured the whole empire.