The title Duke of Berwick (/ˈbɛrɪk/) was created in the Peerage of England on 19 March 1687 for James FitzJames, the illegitimate son of King James II and Arabella Churchill. The title refers to the town of Berwick-upon-Tweed in England by the border with Scotland. At the same time the titles Baron Bosworth and Earl of Tinmouth were created which are subsidiary to the dukedom.
The peerage and its subsidiary titles were generally considered to have been forfeit by the English parliament in 1695, when the Duke was attainted following the enforced exile of his father. The College of Arms in its Roll of the Peerage does not list any such title which means it is non-existent today in England.
Nevertheless, the titles were recognized in France as de facto Jacobite Peerages by King Louis XIV, this to please the exiled King James II & VII, along with other Jacobite Peerages recognized in France, like Duke of Perth, Duke of Melfort, etc. On 13 December 1707, King Philip V confirmed or issued the title in Spain, and conferred the dignity Grandee of Spain to James FitzJames, 1st Duke of Berwick. The Grandeeship is attached to the Spanish title of Duke of Berwick.