He joined the Royal Navy at the outbreak of the wars with Revolutionary France in 1793 at the age of 17, rising to the rank of Post-Captain by 1808. He had an exciting naval career (to match that of the fictional Horatio Hornblower), causing the French to give him the nickname 'le loup des mers' or 'The Sea Wolf'.
Apart from this, he pursued a very active political career, as a staunch campaigner for parliamentary reform in Britain, being allied with such Radicals as William Cobbett and Henry 'Orator' Hunt.
After being falsely accused as a conspirator in a Stock Exchange fraud in 1815, he was expelled from the Royal Navy, and later joined the fight for the independence of the South American colonies from Spain and Portugal.