LANCASTER, THOMAS, EARL OF (c. 1277-1322), was the eldest son of Edmund, earl of Lancaster and titular king of Sicily, and a grandson of the English king, Henry III. ; while he was related to the royal house of France both through his mother, Blanche, a granddaughter of Louis VIII., and his step sister, Jeanne, queen of Navarre, the wife of Philip IV. A minor when Earl Edmund died in 1296, Thomas received his father's earldoms of Lancaster and Leicester in 1298; he became prom inent in English affairs after the accession of his cousin, Edward II., in July 1307. Having married Alice (d. 1348), daughter and heiress of Henry Lacy, earl of Lincoln, and added the earldom of Derby to those which he already held, he was marked out both by his wealth and position as the leader of the barons in their resistance to the new king. With his associates he secured the banishment of the royal favourite, Piers Gaveston, in 1308; com pelled Edward in 1310 to surrender his power to a committee of "ordainers," among whom he himself was numbered ; and took up arms when Gaveston returned to England in Jan. 1312. Lan caster, who had just obtained the earldoms of Lincoln and Salis bury on the death of his father-in-law in 1311, drove the king and his favourite from Newcastle to Scarborough, and was present at the execution of Gaveston in June 1312. After lengthy efforts at mediation, he made his submission and received a full pardon from Edward in Oct. 1313; but he refused to accompany the king on his march into Scotland, which ended at Bannockburn, and took advantage of the English disaster to wrest the control of affairs from the hands of Edward.
In 1315 he took command of the forces raised to fight the Scots, and was soon appointed to the "chief place in the council," while his supporters filled the great offices of State, but he proved totally incompetent. The capture of Berwick by the Scots in April 1318 led to a second reconciliation with Edward. A formal treaty, made in the following August, having been ratified by parliament, the king and earl opened the siege of Berwick; but the undertaking was quickly abandoned. Lancaster was suspected of intriguing with the Scots, and his lands were spared when Robert Bruce ravaged the north of England. In 1321, when the Despensers were banished, war broke out again between himself and the king. He surrendered after a skirmish at Boroughbridge. Taken to his own castle at Pontefract, where the king was, he was condemned to death as a rebel and a traitor, and was beheaded near the town on March 22, 1322. He left no children.
Although a coarse, selfish and violent man, Lancaster's memory was long cherished, especially in the north of England, as that of a defender of popular liberties.
See Chronicles of the Reigns of Edward I. and Edward II., ed. W. Stubbs (1882-83) ; and W Stubbs, Constitutional History, vol. ii. (Oxford, 5896).