The title of Earl of Desmond (Irish: Iarla Deasmumhan) has been held historically by lords in Ireland, first as a title outside of the peerage system and later as part of the Peerage of Ireland.
The original Barony of Desmond in the province of Munster was held by descendants of Thomas FitzMaurice FitzGerald, Lord of O'Connelloe. Thomas was a younger son of Maurice FitzGerald, Lord of Lanstephan, a key supporter of Lord Pembroke ("Strongbow") in his 1169 invasion of Ireland. Maurice was the founder of the Cambro-Norman FitzGerald dynasty in Ireland. Being descended from a younger son of Maurice FitzGerald, the House of Desmond was a cadet branch of the Irish Geraldines; the senior branch, the House of Kildare, ancestors of the Dukes of Leinster, was founded by Thomas's elder brother, Gerald FitzMaurice FitzGerald, 1st Lord of Offaly.
Thomas's son, John FitzThomas FitzGerald, became the first Baron Desmond upon receiving, for his homage and service, a grant in 1259 of the lands of Decies and Desmond from Prince Edward of England. Before passing to Edward, these lands had been held by Thomas FitzAnthony, the father of John's wife Margery FitzAnthony.
The title Earl of Desmond was first created for Maurice FitzGerald, 4th Baron Desmond in approximately 1329. Over time, according to English sources, the FitzGerald family became highly assimilated to the local Irish culture. The final Earl of Desmond of this creation was Gerald FitzGerald, the 15th (or, by some counts, the 16th) Earl. The FitzGeralds had resisted the Reformation of King Henry VIII and, after the failure of the first and second Desmond Rebellions, the 15th Earl was defeated and killed by forces loyal to Queen Elizabeth I on 11 November 1583. His title, along with the enormous estates of his family, were forfeit to the English Crown. His nephew, James FitzThomas FitzGerald, attempted to regain control of both during the Nine Years War, but he was captured by the English and executed in 1603.
The second creation was in 1600 for James FitzGerald, who was also created Baron Inchiquin. These titles became extinct on his death the next year.
The third creation was in 1619 for Richard Preston, 1st Lord Dingwall, who was also created Baron Dunmore. On his death in 1628 the Earldom and Irish Barony became extinct while the Scottish Lordship of Parliament passed to his daughter Elizabeth Preston, who married the 1st Duke of Ormonde.
The fourth creation was in 1628 for George Feilding, 1st Viscount Callan. For information on this creation, see the Earl of Denbigh.
Earl of Desmond Wikipedia
The coat of arms of the Geraldine earls of Desmond, blazoned ermine a saltire gules, with the ermine a mark of cadency relative to the senior Kildare branch of the Geraldines (whose arms are more simply blazoned "argent a saltire gules"), contributed to the design of the arms granted to United States President John Fitzgerald Kennedy by the Chief Herald of Ireland, as President Kennedy is believed to have descended on his mother's side from the Desmond Geraldines. The crest shows a man in armour on horseback, facing to the right.
The motto appearing beneath the Desmond arms was "Shanid Abu," in English "Shanid to victory," a reference to the Desmond stronghold of Shanid Castle.
Thomas FitzMaurice FitzGerald, Lord of O'Connelloe, was the progenitor of the Geraldine House of Desmond, and thus the patrilineal ancestor of the Barons Desmond, and of the earls of Desmond of the first creation.
Thomas FitzMaurice FitzGerald was the son of Maurice FitzGerald, Lord of Lanstephan, founder of the Irish Geraldines. Through Maurice's mother Nest ferch Rhys ap Tewdwr, the House of Desmond traced descent in the female line from the House of Dinefwr.
Over a century after Thomas's death, Gerald FitzGerald, 3rd Earl of Desmond, married Eleanor Butler. Through her, John FitzGerald, 4th Earl of Desmond and all subsequent Geraldine earls of Desmond could trace descent through Eleanor de Bohun to Elizabeth of Rhuddlan, daughter of King Edward I of England of the House of Plantagenet by his queen, Eleanor of Castile of the House of Burgundy.John FitzThomas FitzGerald, 1st Baron Desmond (died 1261) (son of Thomas FitzMaurice FitzGerald)
Thomas FitzMaurice FitzGerald, 2nd Baron Desmond (died 1298) (grandson of preceding)
Thomas FitzThomas FitzGerald, 3rd Baron Desmond (1290–1307) (son of preceding)
Maurice FitzThomas FitzGerald, 4th Baron Desmond (died 1356) (brother of preceding; created Earl of Desmond in 1329)
There are several numbering schemes for these earls, depending in part on whether one includes Nicholas as the 3rd Earl. Nicholas suffered from mental developmental disabilities, being described in contemporary records as "an idiot." Nicholas died without issue, and was largely passed over for practical purposes by his younger brother, Gerald FitzGerald, 3rd Earl of Desmond. Here, Nicholas is not numbered among the earls, leading much of this list to differ from the traditional numbering scheme.
Also affecting the various numbering schemes is how one deals with the dispute over the succession to Thomas FitzGerald, 11th Earl of Desmond. Here, the de facto and de jure 12th earl are counted as together comprising the twelfth and the thirteenth in the series, allowing for the traditional numbering to be retained for the 14th and 15th earls.Maurice FitzGerald, 1st Earl of Desmond (died 1356) (new creation)
Maurice FitzGerald, 2nd Earl of Desmond (1336–1358) (son of preceding)
Gerald FitzGerald, 3rd Earl of Desmond (died 1398) (half-brother of preceding)
John FitzGerald, 4th Earl of Desmond (died 1399) (son of preceding)
Thomas FitzGerald, 5th Earl of Desmond (c. 1386–1420) (son of preceding)
James FitzGerald, 6th Earl of Desmond (died 1463) (the "Usurper," paternal uncle of preceding)
Thomas FitzGerald, 7th Earl of Desmond (died 1468) (son of preceding)
James FitzGerald, 8th Earl of Desmond (1459–1487) (son of preceding)
Maurice FitzGerald, 9th Earl of Desmond (died 1520) (brother of preceding)
James FitzGerald, 10th Earl of Desmond (died 1529) (son of preceding)
Thomas FitzGerald, 11th Earl of Desmond (1454–1534) (paternal uncle of preceding)
John FitzGerald, de facto 12th Earl of Desmond (died 1536) (brother of preceding, paternal granduncle of James FitzGerald, de jure 12th Earl of Desmond)
James FitzGerald, de jure 12th Earl of Desmond (died 1540) (grandson of Thomas FitzGerald, 11th Earl of Desmond, grandnephew of John FitzGerald, de facto 12th Earl of Desmond)
James FitzGerald, 14th Earl of Desmond (died 1558) (son of John FitzGerald, de facto 12th Earl of Desmond)
Gerald FitzGerald, 15th Earl of Desmond (c. 1533–1583) (son of preceding; forfeit 1582)
James FitzThomas FitzGerald the Sugán Earl, died in Tower of London c. 1607
James FitzGerald, 1st Earl of Desmond (1571–1601) (known as the "Tower Earl of Desmond")
Richard Preston, 1st Earl of Desmond (died 1628) (extinct)
See: Earl of Denbigh