In 1387 Henry joined the Lord Appellants who opposed King Richard II's court favourites and took part in the battle of Radcot Bridge where Robert de Vere, Richard's favourite was defeated. A year later Henry returned to the king's side possibly because his father, John of Gaunt, had returned from Spain. In 1390 Henry took part in an expedition to Lithuania where he joined the Teutonic Knights in a local conflict. He later took a Grand Tour of Europe on his way to Jerusalem, visiting the important European states and their leaders.
In 1397 several of the Lords Appellants were arrested and convicted of treason. Henry was not included, but in 1398 Henry was involved in a dispute with Thomas Mowbray. Mowbray, as one of the Appellants, spoke to Henry of his concerns that the King would convict him of treason as well. Henry informed the King but Mowbray denied speaking to Henry. The dispute was to be settled by a duel at Coventry in September 1398 but the King decided to banish both men, Henry for ten years and Mowbray for life.
John of Gaunt died in 1399. King Richard then banished Henry for life and confiscated Gaunt's property and Henry's inheritance. Richard's actions were worrying for many Earls and Barons who relied on their inheritance to retain power and status. Henry decided to take matters into his own hands and claim the English throne for himself. Henry saw his chance when Richard left England for Ireland to put down a revolt. Henry landed in Yorkshire in July. He marched south collecting Lancastrian supporters as he went. By the end of July Henry had the support of key Barons and when Richard returned from Ireland the King was captured. Henry was not the true heir to the throne. The next in line was the Earl of March who was only eight years old. Henry convinced Parliament that the country needed strong leadership and on October 13, 1399, Henry was crowned at Westminster Abbey.
While Richard was imprisoned his supporters plotted to return the old King to the throne by killing Henry and his family. Henry dealt with the rebellion and Richard was murdered in Pontefract Castle.
What started as a land dispute between Owain Glyndwr, a wealthy land owner in Wales and his rival Lord Grey of Rutin quickly escalated into a revolt when Henry sided with Rutin and awarded him the land. Glyndwr's revolt spread and he proclaimed himself the Prince of Wales. He was joined by the Tudor brothers from Anglesey and began guerrilla warfare against the English in the North of Wales and the Marcher Lords in the centre. Henry IV moved into North Wales to try and stop the rebellion but he was not able to deal with the Welsh rebels who were more skilled at fighting in the terrain. The conflict widened when Edmund Mortimer was captured by Glyndwr and when Henry refused to pay a ransom to get him freed, Mortimer sided with the Welsh rebel and even married his daughter. Henry put Hotspur (Henry Percy) in charge of subduing the Welsh in North Wales, but Hotspur developed several complaints against the king and joined the rebellion. At the battle of Shrewsbury on 21st July 1403 Henry managed to defeat and kill Hotspur before his army could join up with Mortimer. The rebellion was joined by others in the north including Archbishop Scrope, but Henry dealt with them all and when Mortimer was killed at the Harlech Castle in 1408 the rebellion was over.
Henry suffered from a skin complaint similar to eczema and this became so severe in 1408 and 1409 that he was immobilised. Henry trusted Arundel, Archbishop of Canterbury, to act as Chancellor and run the country while he was unable to, but pressure was put on him to resign. Prince Henry took his place. Arundel returned in 1411 during a serious dispute between the king and his son. It was suggested that the king should abdicate but Henry refused. The king died from the illness on 20 March 1413.