Roger de Clare¹ {M} [P19] = Maud de St. Hilary {F} [P66]

Roger de Clare:

Born AFT 1115
Died 1173
5th Earl of Clare, 3rd Earl of Hertford

Richard's youngest son Roger, who succeeded his father as earl in 1152, also campaigned in Wales and either built or reconditioned a number of strategic castles, including:
Castell Hywel: Between Lampeter & Newcastle Emlyn. Destroyed by the Welsh in 1136 and rebuilt in 1153.
Aberdyfi (Aberdovey)
Dineirth: A motte-and-bailey castle near Aberystwyth destroyed in 1208. Some signs of masonry.
Llanrhystud
Most of the castles above have long since disappeared from the landscape, however, another branch of the de Clare family (the junior branch) was to leave an even more indelible mark on castle building in Wales. Indeed, many claim that Gilbert de Clare's masterpiece at Caerphilly represents a major turning point in castle design and construction in Britain.

Chronology

1152 suceeded his brother Gilbert in the title and estates
1153 signed Treaty of Westminster
1157 conquered part of Cardigan
1159 defeated by Rhys ap Gruffudd
1160-1 in France
1163 refused Archbishop Becket's claim for homage for Tonbridge Castle
1171 again defeated by Rhys

Maud de St. Hilary:

Alias de Clare

Richard, Earl of Hereford de Clare {M} [P67] = Amicia of, Countess of Gloucester Gloucester {F} [P71] > Family [F18]

Married 1180
Richard, Earl of Hereford de Clare:

Born 1153
Died 1217
Inherited the title Earl of Gloucester from his wife, and passed it down to his son on his death in 1217.

Amicia of, Countess of Gloucester Gloucester:

Alias de Clare

John de Clare {M} [P68]

Mabel de Clare {F} [P69] = William Helion {M} [P118] > Family [F29]

Aveline de Clare {F} [P70] = Geoffrey, Earl of Essex 4th FitzPiers {M} [P90] > Family [F22]

Married Sunday 29 May 1205
Aveline de Clare:

Alias Aveline de Mountchesney

= William de Mountchesney {M} [P87] > Family [F21]

1 : "The Dictionary of National Biography Volume VI"; Page 396-397; Secondary evidence
1a: "The de Clare Family"; Page 1; Questionable