Robert de Ferrers, being a minor at the time of his father's decease, the queen and Peter de Savoy gave 6,000 marks for the custody of his lands during his minority. His lordship, when arrived at manhood, became one of the most active of the discontented nobles arrayed against Henry III and, commencing his career by the plunder and destruction of Worcester, the king, to retaliate, sent a force under Prince Edward into the cos. of Stafford and Derby, which wasted the earl's lands with fire and sword and demolished his castle at Tutworth. His lordship, afterwards joining with Montfort, Earl of Leicester, and Clare, Earl of Gloucester, participated in the victory achieved at Lewes, in Sussex, wherein the king and the prince were made prisoners, but continuing to adhere to Leicester, he was defeated with that nobleman by his former companion in arms, the Earl of Gloucester, at Evesham, and obliged to throw himself upon the mercy of the king, which, in consideration of a cup of gold, adorned with previous stones (obtained from Michal de Tony, upon a mortgage on one of his manors in Northamptonshire), and 1,500 marks, was extended to him and he received a full pardon for all his misdemeanours, the king undertaking to protect him against Prince Edward and others toward whom, at any time during the troubles, he had done wrong, upon condition that, if he should transgress against, he was without hope of favour, to be wholly disinherited. For the strict observance of which provision, the earl not only obliged himself by special charter, then freely sealed to the king, but by his oath of allegiance at the time renewed.
The charter and oath, however, were but feeble restraints upon his lordship for in the very next spring we find him again at the head of a powerful army in the northern part of Derbyshire, and soon after defeated in a pitched battle at Chesterfield by Prince Henry, eldest son of the King of Almaine. Here, his lordship was amongst those who made their escape from the field but, hiding himself under some sacks of wool in a church, he was there discovered through the treachery of a woman and thence conveyed a prisoner to London, whereupon he was totally disinherited, by the parliament then sitting at Westminster, of the Earldom of Derby as well as of his territorial possessions, the greater part of which were conferred by the king upon his 2nd son, Edmund (surname Crouchback), Earl of Leicester and Lancaster, to whom many writers of authority attribute also the dignity of Earl of Derby, but Dugdale expressly says, "although he (the prince) had possession of the greater part of this Robert's land and exercised (perhaps) the power of earl in that county, I am not satisfied that he really was Earl of Derby; in regard, I cannot find that the same Edmund had any patent of creation to that honour as he had to those of Leicester and Lancaster." It seems that this unfortunate nobleman continued in confinement about three years, but in the 53rd Henry III [1269] there was so much interest made for him that the king accepted of security, whereby he might receive satisfaction for his lordship's misdemeanours, and issue his precept to Prince Edmund to make restitution of his lands; when an agreement was entered into between the disinherited earl and the prince, by which the latter, for the sum of £50,000 to be paid at once upon a certain day, was to relinquish all interest in the lands; but that payment not being made good, the securities to the covenant passed over the lands to Prince Edmund and his heirs for ever. Subsequently, however, the ousted lord instituted a suit in the Court of King's Bench against the prince for the restitution of the property upon the allegation that the agreement he had sealed was extorted from him when a prisoner and under apprehension of his life; but after divers pleadings, a decision of the court in the beginning of Edward I's reign confirmed the lands to Prince Edmund.
This Robert de Ferrers, last Earl of Derby of that family, m. 1st, Mary, dau. of Hugh le Brun, Earl of AngoulÍme, and niece of King Henry III, by whom he had no issue; and 2ndly, Eleanore, dau. of Ralph, Lord Basset, by whom he had an only son, John, who inherited Chartley Castle. The earl d. 7th Edward I [1279], the last Earl of Derby of the house of Ferrers. [Sir Bernard Burke, Dormant, Abeyant, Forfeited, and Extinct Peerages, Burke's Peerage, Ltd., London, 1883, p. 197, Ferrers, Earls of Derby]