What makes Roland change his mind and follow Oliver's advice?
The point at which Roland changes his mind and follows Oliver's advice is a pivotal moment in the text. However, it would be inaccurate to say Roland ever followed Oliver's advice, for, when Roland did decide to sound for help, Oliver rebuked him, saying,
Nay, it were foul disgrace On your noble kindred to wreak such wrong; They would bear the stain their lifetime long. Erewhile I sought it, and sued in vain; But to sound thy horn thou wouldst not deign. Not now shall mine assent be won, Nor shall I say it is knightly done. (stanza 149)
Thus, Roland goes against the advice of his close compatriot on two accounts. It is important to recall that when Roland first refused to blow his horn, he had not seen the true extent of Marsilla's forces. He knew of them only through Oliver's description. Thus, he had no certain knowledge of the odds against his small force. It is only after fighting and losing many good men that he realizes the dire situation. He calls for help because he fears defeat at the hands of his enemy and hopes for salvation from Charles' retinue.