Shrewsbury was the chief English military commander in the last phase of the Hundred Years' War against French. He was made marshall of France for English King Henry VI in 1436 after he prevented Normandy from falling to the French. He was killed in an attempt to lift the French siege of the English castle of Castillon in Guyenne. This became the last battle of the Hundred years' War, though no peace treaty was signed to formally end hostilities until 1574 at Piquigny."
-- Encyclopaedia Britannica, Electronic Edition 1996, articles "Shrewsbury, John Talbot, 1st earl of" and "Castillon, Battle of"
Here are further details from Burke's Peerage
1st Earl of Shrewsbury, K.G., summoned to Parliament 1409 as "Johannes Talbot de Furnyvall". He was appointed 1412 Lord Justice of Ireland, and 1414 Lord Lieut. of Ireland, he governed there for 7 years. This Lord Talbot, whom Shakespeare terms "the great Alcides of the field" was one of the most renowned captains of the warlike age he lived in. His earlier feats of arms were under Henry V in France, at the siege and capture of Meaux, and he seems to have inherited the heroic spirit of his royal master.
He gloriously sustained the cause of Henry VI throughout his French realm, in battle after battle, until the very name of Talbot became a terror to the Frenchmen. He was, for a moment, checked in his career by the Maid of Orleans, at Patay, 1429, when, his army being routed, he was taken prisoner. He was exchanged for Ambrose de Lore, a celebrated French partisan, and was soon in activity again, the master-mind and master-director of the fierce contest in France, doing good and effective service every day. In reward he was created, 20th May 1442, EARL OF THE COUNTY OF SALOP, or as usually styled, EARL OF SHREWSBURY.
He was subsequently re-constituted Lord Lieut. of Ireland, and elevated to the Peerage of that kingdom, 17 July 1446, as EARL OF WATERFORD, having been appointed at the same time Lord High Steward of Ireland. After this he went once more to fight in France. He commanded a fleet, landed and took Falaise; as Lieut. of the Duchy of Acquitaine, landed in Medoc and made Bordeaux surrender and the surrounding minor towns send in instant submission.
He thence advanced to the relief of Chastillon, and met the besieging French army commanded by their then greatest leader, Dunois, Bastard of Orleans. In the battle which ensued, 20 July 1453, Talbot, in the sixty-third year of his age, received a wound in the head, which proved immediately mortal. He had been victorious in 40 different battles and dangerous skirmishes; his death proved fatal to the English dominion in France, which never flourished afterwards.