In the Battle of Roncevaux Pass in 778, the rearguard of the Frankish army, under the command of Roland, was obliterated due to an ambush by the Basque army, an event made famous in La Chanson de Roland.

(A) In the Battle of Roncevaux Pass in 778, the rearguard of the Frankish army, under the command of Roland, was obliterated due to an ambush by the Basque army, an event made famous in La Chanson de Roland

(B) In the Battle of Roncevaux Pass in 778, the Basque army ambushed the Frankish army, the rearguard of the Frankish army, under the command of Roland, was obliterated, and the event was made famous in La Chanson de Roland

(C) La Chanson de Roland made famous the obliteration, due to an ambush by the Basque army, of the rearguard of the Frankish army, under the command of Roland, at the Battle of Roncevaux Pass in 778

(D) In La Chanson de Roland, the Basque army ambushed the rearguard of the Frankish army, under the command of Roland, and obliterated them, and this event was famous at the Battle of Roncevaux Pass in 778

(E) In the Battle of Roncevaux Pass in 778, the rearguard of the Frankish army, under the command of Roland, ambushed and obliterated by the Basque army, an event made famous in La Chanson de Roland

This question discusses the legendary Battle of Roncevaux Pass, one of the only defeats of Charlemagne's long career, and it mentions that gorgeously beautiful medieval French poem, La Chanson de Roland.

This question, among other things, explores the "due to" structure. When is this structure correct or incorrect? You can see a full discussion of this point, as well as the OE for this difficult question, at this blog:
GMAT Sentence Correction: the "Due To" Mistake