Battle of Atapuerca
1054 CE.
Shown on the map at 42.350°, -3.517°.
The Battle of Atapuerca was fought on 1 September 1054 at the site of Piedrahita ("standing stone") in the valley of Atapuerca between two brothers, King García Sánchez III of Navarre and King Ferdinand I of Castile. The Castilians won and King García and his favourite Fortún Sánchez were killed in battle. Ferdinand reannexed Navarrese territory he conceded to García 17 years earlier after his brother's assistance at Pisuerga.
Text from the Wikipedia article Battle of Atapuerca, licensed CC BY-SA 4.0.