William Montagu was born in about 1275, the son and heir of Simon de Montagu, 1st Baron Montagu (d. 26 September 1316), by either his first wife, Hawise de St Amand (died 1287), daughter of Amaury de St Amand, or his second wife, Isabel, whose parentage is unknown.
The Montagu family was of Norman origin, later prominent in the West Country of England.
They held extensive lands in Somerset, Dorset and Devon.
From his father's inquisition post mortem, he is known to have had two brothers, John Montagu and Simon Montagu.
William Montagu was born in about 1275, the son and heir of Simon de Montagu, 1st Baron Montagu (d. 26 September 1316), by either his first wife, Hawise de St Amand (died 1287), daughter of Amaury de St Amand, or his second wife, Isabel, whose parentage is unknown. The Montagu family was of Norman origin, later prominent in the West Country of England. They held extensive lands in Somerset, Dorset and Devon. From his father's inquisition post mortem, he is known to have had two brothers, John Montagu and Simon Montagu.
William Montagu, 2nd Baron Montagu