Don Juan, begun in July 1818, is unfinished, and Byron worked on it until the year of his death in 1823. It is a satirical poem which attacks the betrayals and hypocrisies of Byron's age of supposed progress.
He changes the original Don Juan, an incontinent and manipulative sexual predator, into a charming, well-meaning, kind-hearted young man more acted upon by women. Through this device of naïveté Byron exposes the "cant" of his age, mocks its institutions and failures of ideal and belief.
The poem is ironically dedicated to Southey who Byron addresses contemptuously as "turn'd out a Tory at/Last", one who has betrayed the cause of Liberty and now supports Tyranny.
Byron's friends and agent considered the poem to be dangerous and immoral, Hobhouse noting its "blasphemy and bawdy". But for Byron, in the poem's immorality lay its social truth: "But now I'm going to be immoral", he writes, "I mean to show things really as they are."