What epic poem features Roland, a commander in Charlemagne's rear guard?

The epic poem featuring Roland as commander of Charlemagne’s rear guard is The Song of Roland. Written in Old French, it is the best-known of the chansons de geste, medieval poems celebrating heroic deeds and aristocratic warfare.

The poem dramatizes the Battle of Roncevaux Pass. In its version of events, the traitor Ganelon reveals how Charlemagne’s army can be ambushed as it returns from Spain. Roland leads the rear guard with companions including Oliver and Archbishop Turpin. Surrounded by enemies, Roland delays blowing his olifant, or signal horn, because Oliver sees that refusal as reckless pride.

When Roland finally sounds the horn, Charlemagne hears it and turns back, but the rear guard has already been destroyed. Roland dies after attempting to break his sword Durendal and commending his soul to God. These details belong to the poem’s heroic tradition rather than a strictly historical account.

The historical Roland was a Frankish military commander who died in a Basque attack in 778. The surviving poem was composed centuries later, probably between about 1040 and 1115, and greatly reshaped that event.