Prince Charles succeeds his father as 2d Duke of Edinburgh. There are now three living British princes with the title “2d Duke of…”; how often have there been even two?
Since the 14th century most of the sons of British monarchs are given ducal titles, 71 of them by my count; but only 14 of these have passed the title to a male heir. (Sixteen times the ducal title was extinguished when its holder became King.) So it’s historically rare for two such successors to exist at the same time. Unless we count 1420–25, when a second duke of York and a second duke of Albany coexisted in different kingdoms, the first such occasion was 1851.
George, 2d duke of Cambridge, succeeded his father (the youngest son of George III) in 1850, and died in 1904.
George, 2d duke of Cumberland and Teviotdale (also the last king of Hanover) succeeded to his titles in 1851, making the first such duo. He died in 1878, succeeded by Ernest Augustus, 3d duke, one of four persons stripped of British peerages in 1919 under the Titles Deprivation Act.
Charles Edward, 2d duke of Albany (also the last reigning duke of Saxe-Coburg) was the posthumous son of Victoria’s last son Leopold, who died of hæmophilia at 30 in 1884. He made the first trio. He too lost his British titles in 1919.
Alastair, 2d duke of Connaught and Strathearn, succeeded his grandfather in 1942 and died in strange circumstances 15 months later. Although the dukedom was created for a son of Queen Victoria, Alastair was not a Prince, because since 1917 that title is restricted to two generations.
Prince Edward became 2d duke of Kent when his father (son of George V) died in an air crash in 1942. He is still living, and has eight potential successors.
Prince Richard succeeded as 2d duke of Gloucester in 1974, making a new duo.
And as of yesterday there is now a 2d duke of Edinburgh, making the second trio. Edinburgh seems to be lucky: other than those mentioned above, the only second-generation royal dukes since the union of crowns (1603) were Edinburgh (1751–1760) and Gloucester & Edinburgh (1805–1834).
That 2d duke of Ed. succeeded to the crown seventeen months later, extinguishing that dukedom. The new king recreated the title for his youngest brother, as was expected, but surprisingly only for life; Edward’s son will succeed him as earl of Wessex and Forfar but not as duke.