His hazardous venture of crossing Olympus by the pass of Lapathus westward of Tempe, leaving behind one division to face the garrison of the pass, and making his way with his main force through impracticable denies to Heracleum, is not excused by the fact of its success.

The main part of the army passed through the Pyrenees unmolested, but the rear guard of twenty thousand men, under Roland, was attacked by a superior force of Saracens in ambush, as it was passing through the denies of Roncesvalles.