William MARSHAL , 1st Earl of Pembroke

  General Notes:

William Marshal, 1st Earl of Pembroke was born in 1146. He was the son of John FitzGilbert and Sybil de Salisbury.2,3 He married Isabella de Clare, Countess of Pembroke, daughter of Richard FitzGilbert de Clare, 2nd Earl of Pembroke and Aoife MacMorrough, in August 1189 at London, England. He died on 14 May 1219 at Caversham, Berkshire, England.
William Marshal, 1st Earl of Pembroke also went by the nick-name of William 'the Elder'. He was created 1st Earl of Pembroke [England] on 27 May 1199.1
Children of William Marshal, 1st Earl of Pembroke and Isabella de Clare, Countess of Pembroke

Sibyl Marshal+4
Walter Marshal, 5th Earl of Pembroke d. 24 Nov 1245
Gilbert Marshal, 4th Earl of Pembroke5 d. 27 Jun 1241
Eve Marshal+6 d. b 1246
Anselm Marshal, 6th Earl of Pembroke d. 22 Dec 1245
Johanna Marshal
Margaret Marshal+7 b. c 1189
William Marshal, 2nd Earl of Pembroke b. c 1190, d. 24 Apr 1231
Richard Marshal, 3rd Earl of Pembroke b. 1191, d. 16 Apr 1234
Matilda Marshal+8 b. 1192, d. 27 Mar 1248
Lady Isabella Marshal+9 b. 9 Oct 1200, d. 17 Jan 1240

https://en.wikipedia.org/wiki/William_Marshal,_1st_Earl_of_Pembroke
William Marshal, 1st Earl of Pembroke (1146 or 1147 \endash 14 May 1219), also called William the Marshal (Norman French: Williame li Mareschal,[1] French: Guillaume le Maréchal), was an Anglo-Norman soldier and statesman. He served five English kings \endash Henry II, his sons the "Young King" Henry, Richard I, John, and John's son Henry III.

Knighted in 1166, he spent his younger years as a knight errant and a successful tournament competitor; Stephen Langton eulogized him as the "best knight that ever lived." In 1189, he became the de facto Earl of Pembroke through his marriage to Isabel de Clare, though the title of earl would not be officially granted until 1199 during the second creation of the Pembroke Earldom. In 1216, he was appointed protector for the nine-year-old Henry III, and regent of the kingdom.

Before him, his father's family held a hereditary title of Marshal to the king, which by his father's time had become recognized as a chief or master Marshalcy, involving management over other Marshals and functionaries. William became known as 'the Marshal', although by his time much of the function was delegated to more specialized representatives (as happened with other functions in the King's household). Because he was an Earl, and also known as the Marshal, the term "Earl Marshal" was commonly used and this later became an established hereditary title in the English Peerage.
https://en.wikipedia.org/wiki/William_Marshal,_1st_Earl_of_Pembroke
William Marshal, 1st Earl of Pembroke (1146 or 1147 \endash 14 May 1219), also called William the Marshal (Norman French: Williame li Mareschal,[1] French: Guillaume le Maréchal), was an Anglo-Norman soldier and statesman. He served five English kings \endash Henry II, his sons the "Young King" Henry, Richard I, John, and John's son Henry III.

William married Isabella DE CLARE Countess of Pembroke, daughter of Richard FizGilbert DE CLARE 2nd Earl Pembroke, Earl of Buckingham and Aoife MACMORROUGH. (Isabella DE CLARE Countess of Pembroke was born in 1172 and died in 1220.)