The Battle of Roncevaux Pass in 778 saw a large force of Basques ambush a part of Charlemagne's army in Roncevaux Pass, a high mountain pass in the Pyrenees on the present border between France and Spain, after his invasion of the Iberian Peninsula.
The Basque attack was a retaliation for Charlemagne's destruction of the city walls of their capital, Pamplona. As the Franks retreated across the Pyrenees back to Francia, the rearguard of Frankish lords was cut off, stood its ground, and was wiped out.
Among those killed in the battle was Roland, a Frankish commander.
Wikipedia https://en.wikipedia.org/wiki/Battle_of_Roncevaux_Pass
Address 5 Calle de Nuestra Señora de Roncesvalles, Roncesvalles 31650, Spain
Coordinates 43°0'32.147" N -1°19'11.551" E