His dominance of the province and its inhabitants, both Gaelic and Hiberno-Norman, was deemed sufficiently detrimental to the colony that Richard II of England spent much of the years 1394 and 1395 sparring with him.

MacMurrough-Kavanagh was married to Anglo-Irish noblewoman Elizabeth le Veel, widow of Sir John Staunton of Clane and the only daughter of Sir Robert le Veel.

Such an interracial marriage violated the Statutes of Kilkenny and the Crown thus forfeited Elizabeth's lands, which later became one of the causes of her husband's enmity with the English.

They had three sons: Donnchadh, King of Leinster; Diarmuid Lamhdearg; and Gerald, Lord of Ferns.

[2][3] The 1885 historical novel Art M'Morrough O'Cavanagh, Prince of Leinster: An Historical Romance of the Fourteenth Century by M. L. O'Byrne is a loosely biographical account of his life, written from a nationalist perspective.