Although it was a given right for Marcher Lords to wage private war the King tested this right in this case, first calling them before a court of their Marcher peers, then realising the outcome would be coloured by their likely avoidance of prejudicing one of their greatest rights they were both called before the superior court, the Kings own. At this both were imprisoned by the King, both sentenced to having their lands forfeit for life and de Clare, the Earl of Gloucester, as the aggressor, was fined 10,000 marks, and the Earl of Hereford 1,000 marks.They were released almost immediately and both of their lands completely restored to them – however they had both been taught a very public lesson and their prestige diminished and the King's authority shown for all. Gilbert's first marriage was to Alice de Lusignan, also known as Alice de Valence, the daughter of Hugh XI of Lusignan and of the family that succeeded the Marshal family to the title of the Earl of Pembroke in the person of William de Valence, 1st Earl of Pembroke. They married in 1253, when Gilbert was ten years old. She was of high birth, being a niece of King Henry, but the marriage floundered. Gilbert and Alice separated in 1267; allegedly, Alice's affections lay with her cousin, Prince Edward. Previous to this, Gilbert and Alice had produced two daughters:   After his marriage to Alice de Lusignan was annulled in 1285, Gilbert married Joan of Acre, a daughter of King Edward I of England and his first wife Eleanor of Castile. King Edward sought to bind de Clare, and his assets, more closely to the Crown by this means. By the provisions of the marriage contract, their joint possessions and de Clare's extensive lands could only be inherited by a direct descendant, i.e. close to the Crown, and if the marriage proved childless, the lands would pass to any children Joan may have by further marriage. On 3 July 1290, the Earl gave a great banquet at Clerkenwell to celebrate his marriage of 30 April 1290 with Joan of Acre (1272 – 23 April 1307) after waiting for the Pope to sanction the marriage. Edward then gave large estates to Gilbert, including one in Malvern. Disputed hunting rights on these led to several armed conflicts with Humphrey de Bohun, 3rd Earl of Hereford, that Edward resolved. Gilbert made gifts to the Priory, and also had a "great conflict" about hunting rights and a ditch that he dug, with Thomas de Cantilupe, Bishop of Hereford, that was settled by costly litigation.