Siege of Dorostolon
971 CE.
Shown on the map at 44.119°, 27.260°.
The Siege and Battle of Dorostolon (Silistra) was fought in 971 between the Byzantine Empire and forces of Kievan Rus'. The Byzantines, led by John I Tzimiskes, were victorious.
Text from the Wikipedia article Siege of Dorostolon, licensed CC BY-SA 4.0.