Although Richard the Second's reign began smoothly, he soon fell under control of his dissolute favourites and he began making decisions that would cost him his crown.
The exile of his cousin, Henry of Bolingbroke, proved his downfall. Henry was the first born son of John of Gaunt, Duke of Lancaster, one of Richard's favoured uncles. His exile was politically motivated and deemed unfair. But after hearing of the deprivation of his inheritance when his father died, Henry returned to England.
Obtaining the support of many people, disenchanted by Richard II's reign, Henry captured and imprisoned the King in the Tower of London. Richard formally abdicated in 1399 and died five months later, at the age of 32, under suspicious circumstances in Pontefract Castle.
Henry IV was anointed as the first Lancastrian King of England, and was succeeded by his son, Henry V.
Before Richard had been made to abdicate, he had nominated Roger Mortimer, Earl of March as his heir. March was the grandson of Lionel, Duke of Clarence, second son of Edward III. However, he died one year prior to Richard's abdication and his son Edmund Mortimer was next in line. Edmund's sister Anne Mortimer married Richard, Earl of Cambridge, whose father was Edmund of York, the fourth son of Edward III. The combination of these two formidable bloodlines produced the Yorkist claim to the throne that threatened three generations of Lancastrian Kings.
The Earl of Cambridge was executed during the reign of Henry V after being involved in a rebellion in support of Edmund Mortimer's claim to the throne.
Richard of York, the Earl's son believed his royal descent through Roger Mortimer was stronger than that of Henry VI. He played a major role in governing English interests in France and Normandy, until John Beaufort, Duke of Somerset and cousin to Henry VI, through the illegitimate branch of John of Gaunt, was appointed above York in 1443. He was granted a larger army and advance payment for his army. Meanwhile, York received nothing and at the end of his term, was owed nearly two years wages and was unable to pay his captains and garrisons.
York was credited with doing his appointment admirably and had many honourable and notable successes with the French. However, envy of his prosperity upset those at Court desiring more power. Henry and his close advisors also looked upon York with a degree of suspicion. His Queen, Margaret of Anjou worked upon Henry to replace York. His new appointment was in Ireland, whilst John Beaufort's younger brother, Edmund (now the Duke of Somerset and favoured by the Queen), took his desired lieutenancy of France in 1447.