Edward III declared himself rightful heir to the French throne in 1338, but his claim was denied due to the Salic law. This started what would become known as the Hundred Years' War. Following some initial setbacks, the war went exceptionally well for England; victories at Crécy and Poitiers led to the highly favourable Treaty of Brétigny. Edward's later years were marked by international failure and domestic strife, largely as a result of his inactivity and poor health.

Edward III died of a stroke on 21 June 1377, and was succeeded by his ten-year-old grandson, Richard II. He married Anne of Bohemia, daughter of Charles IV, Holy Roman Emperor in 1382, and ruled until he was deposed by his first cousin Henry IV in 1399. In 1381, a Peasants' Revolt led by Wat Tyler spread across large parts of England. It was suppressed by Richard II, with the death of 1500 rebels.

Henry V succeeded to the throne in 1413. He renewed hostilities with France and began a set of military campaigns which are considered a new phase of the Hundred Years' War, referred to as the Lancastrian War. He won several notable victories over the French, including the Battle of Agincourt. In the Treaty of Troyes, Henry V was given the power to succeed the current ruler of France, Charles VI of France.

Henry V's son, Henry VI, became king in 1422 as an infant. His reign was marked by constant turmoil due to his political weaknesses. The Regency Council tried to install Henry VI as the King of France, as provided by the Treaty of Troyes signed by his father, and led English forces to take over areas of France. It appeared they might succeed due to the poor political position of the son of Charles VI, who had claimed to be the rightful king as Charles VII of France. However, in 1429, Joan of Arc began a military effort to prevent the English from gaining control of France. The French forces regained control of French territory. Hostilities with France resumed in 1449. When England lost the Hundred Years' War in August 1453, Henry fell into mental breakdown until Christmas 1454.