About the work
Semi-opera in five acts by Henry Purcell to a libretto by Thomas Betterton after John Fletcher and Philip Massinger's play "The Prophetess". It premiered in late May 1690 at the Queen's Theatre, Dorset Garden, in London, Purcell's first major work of this kind.
Plot
A prophetess foretells that the soldier Diocles will become emperor and marry Drusilla. After killing his rival Aper ("boar"), he is made co-emperor as Dioclesian but breaks his promise to Drusilla and courts Princess Aurelia instead. Only when the prophetess punishes him with storms and military defeat does Dioclesian abdicate and return to Drusilla.
Cultural significance
The prologue written by John Dryden was banned after its premiere for criticising King William's Irish campaign; the closing masque of Act V remained popular throughout the eighteenth century and is regarded as one of Purcell's most striking pieces for the stage. Dioclesian was the only one of his semi-operas to be published complete during his lifetime.