Henry IV (1367-1413), the king of England from 1399 to 1413, was the first monarch of the Lancastrian dynasty. His reign was marked by the development of parliamentary government in England.

Henry IV was the only son of John of Gaunt, the son of Edward III, and Blanche, the daughter of Henry Grismond, Duke of Lancaster. Known as Henry Bolingbroke after his birthplace in Lincolnshire, he was made a knight of the Garter in 1377. In 1380, at the age of 13, he married Mary de Bohun, the youngest daughter and coheiress of Humphrey, the last Earl of Hereford. They had four sons and two daughters before her death at the age of 24, in 1394. As the Earl of Darby, Henry entered the House of Lords in 1385. In 1387 he supported his uncle Thomas, Duke of Gloucester, in his opposition to Richard II. (Gloucester was also Richard's uncle, and Henry was the King's first cousin...