The original title was Earl of March (not to be confused with the Earls of March and Dunbar of Scottish peerage), which was granted to a Roger Mortimer by Edward II in 1328. He forfeited his title for treason in 1330 but it was restored to his grandson, another Roger, in 1348. Edmund I had been the fifth Earl of March for eleven years when he became King of England in 1409 and the title merged with the throne.
Edmund I’s brother, another Roger Mortimer, became extremely ill in 1413 and he was nursed through his sickness by an otherwise unknown Lady Alicern (a rendering of Alison). Upon his recovery, the two married and Edmund I celebrated Roger’s good health with the first creation of the dukedom under the Peerage of England.
The second creation occurred in 1770, when the young Charles Edmund Mortimer died without heirs. The title would have returned to the throne but a distant relative Alexander Henry Mortimer, the Baron Mortimer of Clun, demonstrated his connection to the Mortimers of Wigmore, the original title holders, by a combination of letters patent and expedition to the Otherworld to prove his Second Sight. Given the time of the creation, he should perhaps be more correctly termed the 1st Duke of March of the first creation of the British Peerage. However, both the family and the Crown prefer to reference the family’s continuity.
The third creation occurred in 1873, when Alexander Henry Mortimer’s grandson, Edmund Alexander, died without legitimate male heirs. The estate was contested by his daughters’ husbands but an illegitimate son, styling himself Edmund Roger Beddoes-Mortimer, stepped forward and demonstrated his right to the Mortimer inheritance with parish records detailing Edmund Alexander Mortimer’s financial support through his childhood and by undertaking an expedition to the Otherworld to prove his Sight. While his legitimate sisters were awarded substantial parts of the estate, Edmund Roger won the family seat of Wigmore and the title. Again, given the time of the creation, the Beddoes-Mortimers should perhaps be more correctly termed the first creation of the dukedom under the United Kingdom‘s Peerage. Again, both the family and the Crown prefer to reference the family’s continuity.
Tradition states that all holders of the dukedom have had Second Sight and all heirs presumptive have proven their right by serving as a Ranger after completing their education. As Second Sight is known to be inherited through the male line, and the title has been passed through male lines only, this suggests that the Royal Mortimers and the various related noble Mortimer lines are the only well documented family that doesn’t have any unexpected genetic twists due to adultery – at least since the days of Edmund I and his brother.