Welsh rebel leader Owain Glyndŵr, having declared himself Prince of Wales, allies himself with the French against King Henry IV of England.

Owain ap Gruffydd, commonly known as Owain Glyndŵr was a Welsh leader, soldier and military commander in the late Middle Ages, who led a 15-year-long Welsh revolt with the aim of ending English rule in Wales. He was an educated lawyer, forming the first Welsh parliament under his rule, and was the last native-born Welshman to claim the title Prince of Wales.

Prince of Wales is a title traditionally given to the male heir apparent to the English, and later, the British throne. The title originated with the Welsh rulers of Gwynedd who, from the late 12th century, used it to assert their supremacy over the other Welsh rulers. However, to mark the finalisation of his conquest of Wales, in 1301, Edward I of England invested his son Edward of Caernarfon with the title, thereby beginning the tradition of giving the title to the heir apparent when he was the monarch's son or grandson. The title was later claimed by the leader of a Welsh rebellion, Owain Glyndŵr, from 1400 until 1415.

Henry IV, also known as Henry Bolingbroke, was King of England from 1399 to 1413. Henry was the son of John of Gaunt, Duke of Lancaster, and Blanche of Lancaster.