Henry IV is proclaimed king of England.

Henry was the eldest surviving son of John of Gaunt, duke of Lancaster, by his first wife, Blanche. Before becoming king, he was known as Henry Bolingbroke, and he received from his cousin Richard II the titles earl of Derby 1377 and duke of Hereford 1397. During the opening years of the reign of King Richard II ruled 1377–99, Henry remained in the background while his father ran the government. When Gaunt departed for an expedition to Spain in 1386, Henry entered politics as an opponent of the crown. He and Thomas Mowbray later 1st duke of Norfolk became the younger members of the group of five opposition leaders—known as the lords appellants—who in 1387–89 outlawed Richard’s closest associates and forced the king to submit to their domination. Richard had just regained the upper hand when Gaunt returned to reconcile the king to his enemies. Bolingbroke then went on Crusade into Lithuania 1390 and Prussia 1392. Meanwhile, Richard had not forgiven his past enmity. In 1398 the king took advantage of a quarrel between Bolingbroke and Norfolk to banish both men from the kingdom. The seizure of the Lancastrian estates by the crown upon John of Gaunt’s death February 1399 deprived Henry of his inheritance and gave him an excuse to invade England July 1399 as a champion of the nobility. Richard surrendered to him in August; Bolingbroke’s reign as King Henry IV began when Richard abdicated on September 30, 1399.

Henry IV used his descent from King Henry III ruled 1216–72 to justify his usurpation of the throne. Nevertheless, that claim did not convince those magnates who aspired to assert their authority at the crown’s expense. During the first five years of his reign, Henry was attacked by a formidable array of domestic and foreign enemies. He quashed a conspiracy of Richard’s supporters in January 1400. Eight months later the Welsh landowner Owain Glyn D?r raised a rebellion against oppressive English rule in Wales. Henry led a number of fruitless expeditions into Wales from 1400 to 1405, but his son, Prince Henry later Henry V, had greater success in reasserting royal control over the region. Meanwhile, Owain Glyn D?r encouraged domestic resistance to Henry’s rule by allying with the powerful Percy family—Henry Percy, earl of Northumberland, and his son Sir Henry Percy, called Hotspur. Hotspur’s brief uprising, the most serious challenge faced by Henry during his reign, ended when the king’s forces killed the rebel in battle near Shrewsbury, Shropshire, in July 1403. In 1405 Henry had Thomas Mowbray, the eldest son of the 1st duke of Norfolk, and Richard Scrope, archbishop of York, executed for conspiring with Northumberland to raise another rebellion. Although the worst of Henry’s political troubles were over, he then began to suffer from an affliction that his contemporaries believed to be leprosy—it may have been congenital syphilis. A quickly suppressed insurrection, led by Northumberland in 1408, was the last armed challenge to Henry’s authority. Throughout those years the king had to combat border incursions by the Scots and ward off conflict with the French, who aided the Welsh rebels in 1405–06.