Berlioz based the libretto of his five—act Grand Opera Les Troyens on books II, the second half of I, and IV of the Aeneid of Virgil, and set it to music which illuminates his vision of Virgil’s epic poem. This thesis compares the story patterns, narrative techniques, themes and content of the two works. Because Virgil uses the technique of retrospective narrative in Book II of the Aeneid, and Berlioz unfolds his story in chronological order, I have used the sequence of Berlioz’s work as the basis for the comparison. The thesis analyses in detail Berlioz’s re—use of Virgil, the points where Berlioz’s treatment coincides with Virgil’s, the points where he diverges from Virgil, arid the main thrust of Berlioz’s argument. The two most important differences which emerge between the two works are the divergent ideas on the gods, and on the conflict between personal love and duty. Whereas pietas and filial duty are central to Virgil’s work, the importance of love between man and woman is central to that of Berlioz. And in Les Troyens the terrific tension between love and duty is illuminated in Act V, where Aeneas must leave Dido even though Berlioz has shown in Act I, with Cassandra and Coroebus, that, fate permitting, such a love can be duty as well. Virgil shows us the gods at work, and carefully attempts to explain their motivation. Berlioz however structures his music—drama so that the gods, only one of whom (Mercury) makes an appearance, are shown to be cruel by their complete indifference to those who invoke them. / PhD Doctorate