Battle of Knjaževac
1913 CE.
Shown on the map at 43.567°, 22.250°.
The Battle for Knjaževac was a minor engagement during the Second Balkan War between the Bulgarian 1st Army and Serbian forces near the town of Knjaževac, fought from 4 to 7 July 1913. Although Bulgarian troops captured the town after heavy fighting, a strategic withdrawal was ordered the next day. Elements of the retreating force were then ambushed by Serbian artillery, resulting in severe losses.
Text from the Wikipedia article Battle for Knjaževac, licensed CC BY-SA 4.0.