Before 1256 Nicholas Segrave 1st Baron Segrave and Maud Lacy were married
On 14 May 1264 the army of Simon Montfort 6th Earl Leicester including Gilbert "Red Earl" Clare 7th Earl Gloucester, 6th Earl Hertford (20) , Henry Hastings (29) and Nicholas Segrave 1st Baron Segrave (26) defeated the army of Henry III King England (56) during the Battle of Lewes at Lewes. Henry III King England (56) , his son the future Edward "Longshanks" I King England (24) , Humphrey Bohun 2nd Earl Hereford, 1st Earl Essex (60) , Richard Cornwall 1st Earl Cornwall (55) , John "Red Comyn" Comyn 1st Lord Baddenoch and John Giffard 1st Baron Giffard Brimpsfield were captured. John Warenne 6th Earl Surrey (33) , John Balliol (56) , Robert Bruce 5th Lord Annadale (49) , Roger Leybourne and William Valence 1st Earl Pembroke fought for the King. Guy Lusignan was killed. Fulk IV Fitzwarin drowned.
On 04 Aug 1265 the army loyal to Henry III King England (57) , led by his son the future Edward "Longshanks" I King England (26) , supported by Gilbert "Red Earl" Clare 7th Earl Gloucester, 6th Earl Hertford (21) , Warin Basingburne and John Giffard 1st Baron Giffard Brimpsfield defeated the rebel army of Simon Montfort 6th Earl Leicester. Roger Leybourne fought and reputedly saved the King's life. Adam Mohaut rescued the King. The rebels Simon Montfort 6th Earl Leicester and his son Henry Montfort were killed. Hugh Despencer 1st Baron Despencer (42) was killed by Roger Mortimer 1st Baron Mortimer Wigmore (34) . The rebels Simon Beauchamp (31) , Ralph Basset 1st Baron Basset Drayton (23) , William "Elder" Devereux (46) , Hugh Troyes, Richard Trussel, Peter Montfort, William Mandeville, William Crepping, William Birmingham, Guy Balliol and Thomas Astley were killed. Henry Hastings (30) , Humphrey Bohun (40) , Nicholas Segrave 1st Baron Segrave (27) , John Vesci, John Fitzjohn and Guy Montfort Count Nola were captured. [Battle of Evesham]