Battle of Roncevaux Pass

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 in 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.

Source: Wikipedia