Arnulf was a younger son of Roger de Montgomery, Earl of Shrewsbury and Mabel de Bellême. He is associated with the earldom of Pembroke Castle and the founding of Pembroke Priory. His birthdate is usually given as 1066 but there is no exact record. The de Bellêmes were part of the Conqueror’s extended kinship network and although de Montgomery didn’t take part int he Conquest he was in England by 1067 where he was granted extensive land holdings. By 1086 he was a very wealthy man having been rewarded with land in Sussex, including manors which had belonged to King Harold, and Shropshire.
It was in 1086 that Arnulf first made his appearance on the known historical record when he witnessed a grant made by his father to a monastery in Normandy. Arnulf is also in evidence rebelling against William Rufus along with the rest of his family in support of Robert Curthose, the Conqueror’s eldest son. The family did not suffer when the rebellion failed and was soon involved in extending its landholdings and power base by an invasion of Wales- specifically the kingdom of Deheubarth – including modern day Dyfed. He is associated with the capture of Nest of Wales pictured at the start of this post with her lover King Henry I – the crowns are to represent their status rather than to suggest that they retired to bed wearing nothing but headgear.
When Roger died in 1094 he was succeeded by his son Hugh and after his death by Robert de Bellême, who was Arnulf and Hugher’s elder brother. De Bellême and his family supported Robert Curthose’s claim to the English throne against that of Curthose’s younger brother King Henry I in 1102. Arnulf had sent his steward, Gerald of Wales, to Ireland to arrange a marriage contract with Muirchertach Ua Briain of Munster which included military assistance as well as a bride. When the rebellion failed, the Montgomery family were banished from England and Arnulf lost Pembroke and the power that he wielded on the marches between England and Wales. The story of their rebellion and subsequent banishment is recounted by Orderic Vitalis, who quite frankly wasn’t totally impressed by the family then or in earlier times.
Following the banishment of the Montgomeries from English shores Arnulf took himself to Ireland and his father-in-law who had no doubt hoped to benefit from Arnulf’s potential as a trading ally. He spent the next twenty years in either Ireland or Normandy. He died circa 1122 at the latest but maybe as early as 1118.
Arnulf’s daughter, Alice, married Maurice FitzGerald the son of Nest the daughter of King Rhys and Arnulf’s steward Gerald of Windsor.