Henry was the son of Edmund de Lacy, Baron of Pontefract, and Alice of Saluzzo, who descended from Amadeus IV, Count of Savoy. Henry was heir to his father, who died when he was a young child, and to his paternal grandmother Margaret de Quincy, Countess of Lincoln who died when he was a teenager. As ward to large and important estates from both his father and more importantly his grandmother, he was educated at court. In 1258 he had inherited his titles and lands from his father, which included Baron of Pontefract, Baron of Halton, and Constable of Chester and in about 1266 he had inherited his titles and lands, which included the Earl of Lincoln, from his paternal grandmother Margaret de Quincy. However being a minor in both cases his inheritance was held in a wardship by his mother, and with the help of his grandmother in the years before her death. In 1272, on reaching the age of majority, which was 21, he became the Earl of Lincoln. He became Chief Councillor to Edward I. While the king was engaged in military conflicts with the Scots, Henry was appointed Protector of the Realm. Following the English Conquest of Wales in 1282 in which Henry took part, he was granted the Lordship of Denbigh. He authorised the building of Denbigh Castle. He went to France with Edmund, Earl of Lancaster, in 1296, and when Edmund died in June of this year, succeeded him as commander of the English forces in Gascony, but returned to England early in 1298. At the battle of Falkirk 1298 and in the siege of Carlaverock 1300 he bore as arms: Or, a lion rampant purpure. In November 1300, he was sent on a mission to Rome to complain to the Pope about injury done by the Scots. Lincoln was Lord of Pontefract, the 10th Baron of Halton, and Lord of Denbigh. He was also the 7thLord of Bowland, so-called Lord of the Fells, being the last member of his family to hold that title. Lincoln was present at Edward's death in July 1307. For a short time he was friendly with the new king, Edward II, and his favourite, Piers Gaveston, but quickly changed his loyalties and joined Earl Thomas of Lancaster and the baronial party, was one of the "ordainers" appointed in 1311 and was regent of the kingdom during the king's absence in Scotland in the same year. Lincoln transferred the Cistercian monastery from Stanlow to Whalley. He is the addressee, or joint composer, of a poem by Walter of Bibbesworth about crusading, La pleinte par entre missire Henry de Lacy et sire Wauter de Bybelesworthe pur la croiserie en la terre seinte.
