The last of those princes,
CONNOR O'BRIEN, who was inaugurated King of Thomond in 1528, died in 1540, when his son was set aside and the principality usurped by his brother,
MURROUGH O'BRIEN, who surrendered his royalty to HENRY VIII, and was created in consequence by His Majesty, in 1543, EARL OF THOMOND, with remainder to his deposed nephew, Donough O'Brien, and BARON INCHIQUIN to his own male heirs; and for the better support of these honours, The King granted and confirmed to him and his male heirs all his lands, possessions, and patronages in Thomond beyond the River Shannon, bishoprics excepted.
His lordship died in 1551, when the Earldom devolved accordingly upon the said
DONOUGH O'BRIEN, who, on surrendering the patent to EDWARD VI, obtained a new grant of the dignities to himself and his male heirs, in 1552, and also possession of all the honours and lands which had fallen to the Crown by the death of his uncle.
From this nobleman the earldom of Thomond passed in regular succession to
HENRY, 8th Earl, and 1st Viscount Tadcaster (1688-1741); at whose decease, without male issue, it expired with his lordship's other honours.
The barony of Inchiquin was inherited by the 1st Earl's son and heir, by Eleanor, daughter of Thomas FitzGerald,
DERMOD, 2nd Baron; to whom his father assigned the castle and lands of Inchiquin and other extensive territorial possessions.
His lordship wedded Margaret, eldest daughter of Donough, 2nd Earl of Thomond; and dying in 1557, was succeeded by his son,
MURROUGH, 3rd Baron (c1550-73), who espoused Mabel, eldest daughter of Christopher, 6th Baron Delvin, and was succeeded at his decease by his son,
MURROUGH, 4th Baron (1563-97), who married Margaret, daughter of Sir Thomas Cusack, LORD CHANCELLOR OF IRELAND, and was succeeded by his son,
DERMOD, 5th Baron (1594-1624), who wedded Ellen, eldest daughter of Sir Edmund FitzGerald, Knight, of Cloyne, and was succeeded at his decease by his eldest son,
MURROUGH, 6th Baron (1614-74), who was advanced to the EARLDOM OF INCHIQUIN in 1654.
The 4th Earl was succeeded, in 1777, by his nephew and son-in-law,
MURROUGH (1726-1808), as 5th Earl; who was created, in 1800, MARQUESS OF THOMOND, and was enrolled amongst the peers of the United Kingdom as Baron Thomond, of Taplow, Buckinghamshire, in 1801.
His lordship had several children by his first consort, Mary, 3rd Countess of Orkney, none of whom lived, however, except MARY, who succeeded to the honours of her mother, as 4th Countess of Orkney, and wedded the Hon Thomas Fitzmaurice.
The 1st Marquess espoused secondly, in 1762, Mary, eldest daughter of John Palmer, of Great Torrington, Devon, and niece of Sir Joshua Reynolds, but had no other issue.
His lordship was thrown from his horse in Grosvenor Square, London, in 1808, and died in consequence of the fall, when the barony of THOMOND, of Taplow, expired; but the Irish honours devolved upon his nephew,
WILLIAM O'BRIEN (1765-1846), as 2nd Marquess, KP.
His lordship married, in 1799, Elizabeth, only daughter and heiress of Thomas Trotter, of Duleek, County Meath, by whom he had issue,
Susan Maria; Sarah; Mary; Elizabeth.The 2nd Marquess was installed a Knight of the Order of St Patrick in 1809.
He died without male issue, when the family honours devolved upon his brother,
JAMES, 3rd Marquess (1769-1855), GCH, an admiral in the Royal Navy, who wedded firstly, in 1800, Eliza Bridgman, second daughter of James Willyams, of Carnanton, Cornwall; and secondly, in 1806, Jane, daughter of Thomas Ottley; and thirdly, in 1847 , Anne, sister of Sir Charles William Flint.
His lordship, however, left no issue, and the marquessate and earldom expired; though the barony of Inchiquin reverted to Sir Lucius O'Brien Bt, as 13th Baron Inchiquin, in 1855.
ROSTELLAN CASTLE, County Cork, stood close to Cork Harbour on the site of an older castle.
It originally belonged to the FitzGeralds, though was taken in 1645 by Murrough O'Brien, 1st Earl of Inchiquin.
The castle was rebuilt at some stage prior to 1750, possibly by the 4th Earl (1700-77), who established the predecessor of the Royal Cork Yacht Club in 1720.
In 1777 the 5th Earl, later 1st Marquess of Thomond, extended and renovated Rostellan; and further alterations were undertaken by the 2nd Marquess.
Thereafter it comprised three storeys, with a five-bay front between two three-sided bows.
A side elevation consisted of four bays and a three-sided bow.
The house front had noticeable string courses and quoins.
A Gothic porch was added in the 19th century; and a substantial Gothic chapel wing with pinnacles and castellated round tower.
Facing the water-front, near the house, there was a battlemented terrace complete with canons, akin to a battery.
The 1st Marquess erected a tower in honour of Mrs Siddons, a house guest.
Following the decease of the 3rd and last Marquess in 1855, Rostellan was purchased by Dr T A Wise.
Sir John Pope-Hennessy, KCMG, formerly of Myrtle Grove, became the next owner; followed by C J Engledow MP.
Rostellan suffered the fate of many fine country houses, in 1944, by demolition.
Thomond arms courtesy of European Heraldry.