Albion and Albanius and its composer, Louis Grabu, have been unjustly dismissed by musical scholars. This thesis seeks to redress that injustice. A documentary biography of Grabu is provided, and a discussion of the inception of Albion and Albanius, detailing the role of each of its creators. The opera is subjected to a thorough examination, including a discussion of: 1) the relationship between the 1685 libretto and the 1687 score; 2) its largescale structure and tonal plan; 3) and its vocal and instrumental writing. These studies reveal that Grabu, in composing the music, Dryden, in writing the libretto, and Betterton, in designing staging, drew upon specific models from Lully's Phaêton (1683). Furthermore, it is shown that Grabu drew upon a thorough knowledge of Lully's other operas: not only the general compositional features and structures, but also specific movements. There is, in addition, evidence suggesting that Grabu borrowed musical ideas and techniques from Purcell's Dido and Aeneas. Information regarding the opera's performance is gathered from the score and developed through comparison with contemporary practices. In particular, the similarities between Grabu's score and those of Lully printed by Ballard suggest that Grabu wrote for an ensemble modelled on that of the Paris Opéra. The dance and staging elements of the opera are examined in the light of information about, and illustrations from, English and especially French productions (particularly the drawings of Berain). Grabu's influence on Purcell, and Dioclesian in particular, is demonstrated. The reception history of Albion and Albanius is explored, and the assertion that Grabu was an incompetent composer and the opera an artistic failure is shown to be unfounded. A modern edition of Albion and Albanius with critical commentary is provided.