Abschwangen massacre
1914 CE.
Shown on the map at 54.500°, 20.761°.
The Abschwangen massacre was a massacre committed by Russian troops during World War I on 29 August 1914 in the occupied village of Abschwangen (now Tishino) near Preussisch Eylau some 30 km (19 mi) south of Königsberg, in which 65 German civilians, including 28 locals and 37 refugees from other places, were killed.
Text from the Wikipedia article Abschwangen massacre, licensed CC BY-SA 4.0.