John's father died in about 1189, and, being under age, he was made the ward of his uncle, William de Braose, 4th Lord of Bramber, Sheriff of Herefordshire and a court favourite.
John was also one of King Henry's allies in fighting the rebellions by the Welsh prince Llywelyn ab Iorwerth and Richard Marshal, Earl of Pembroke.
However, he reportedly fled the Battle of Monmouth in 1233, when Richard Marshal's forces defeated the defenders of the town led by Baldwin III, Count of Guînes, and thereafter devastated the surrounding countryside.
He was made chief bailiff of South Wales in 1242, and at one point had control of Chepstow, Usk, Caerleon, Carmarthen, Builth and Cardigan as well as Monmouth.
[1] His son John, who had been born in about 1225, fell heavily into debt and surrendered his estates, including the lordship of Monmouth, to the crown in 1256.