The title of Duke of Connaught and Strathearn was granted by Queen Victoria of the United Kingdom of Great Britain and Ireland to her third son, Prince Arthur, on 24 May 1874. At the same time, he was also granted the subsidiary title of Earl of Sussex.
Duke of Connaught and Strathearn Wikipedia
By tradition, members of the sovereign's family received titles associated with England, Scotland, Ireland and Wales, the four Home Nations that made up the United Kingdom of Great Britain and Ireland. The Dukedom of Connaught and Strathearn was named after one of the four provinces of Ireland, now known by its modern Irish language-based spelling of Connacht. It was seen as the title that, if available, would henceforth be awarded to the British monarch's third son. The first son was traditionally Duke of Cornwall (in England) and Duke of Rothesay (in Scotland), and would be made Prince of Wales at some point, while the second son would often become Duke of York, if the title was available.
Since the exit of the Irish Free State from the United Kingdom in 1922, titles related to locations in the Free State (and later the Republic of Ireland) have not been awarded (though Prince Edward, Prince of Wales—in 1936 briefly King Edward VIII—was made a Knight of the Order of St Patrick). However, territorial titles relating to Northern Ireland have continued to be awarded.
After Prince Arthur's death in 1942, the title was inherited by his grandson, Alastair. In the absence of any male heirs, the dukedom became extinct when Alastair died, 15 months after his grandfather.
A Canadian military regiment, The British Columbia Regiment (Duke of Connaught's Own), is a Canadian armoured regiment in the 1st Duke's name. A British Indian Army cavalry regiment, the 6th Duke of Connaught's Own Lancers (Watson's Horse), was also named for the 1st Duke.Subsidiary title: Earl of Sussex (1874)
The Prince Arthur, 1st Duke of Connaught and Strathearn (1850–1942), third son of Queen Victoria
Prince Arthur of Connaught (1883–1938), only son of the 1st Duke, predeceased his father
Alastair Windsor, 2nd Duke of Connaught and Strathearn (1914–1943), only child of Prince Arthur of Connaught, died unmarried and without issue
Princess Louise Margaret of Prussia, wife of The Prince Arthur
Princess Alexandra, 2nd Duchess of Fife, was Duchess of Fife in her own right; wife of Prince Arthur of Connaught, who predeceased his father.