John of Gaunt, << gawnt or gahnt >> (1340-1399), Duke of Lancaster, was an English soldier and political leader. Beginning in 1377, he was the power behind the throne during much of the reign of his nephew, King Richard II of England. For nearly 10 years, he fought under his nephew in the Hundred Years’ War (1337-1453) against France. The duke also supported the English philosopher John Wycliffe’s efforts to reform the English clergy (religious leaders).
John was the son of King Edward III of England. He was born in Ghent, Belgium, from which he took his name. He became Duke of Lancaster after the father of his first wife, Blanche of Lancaster, died in 1361. By his marriage in 1372 to Constance, daughter of King Pedro I of Castile (now part of Spain), John claimed the Castilian throne. His son Henry IV was the first English king from the House of Lancaster. After Constance’s death, John married Katherine Swynford, his mistress, in 1396. John died on Feb. 3, 1399.