After the Battle of Hastings in 1066, Duke William of Normandy gained the English Crown and became King William of England, aka William the Conqueror. This technically made the King of England a vassal of the King of France. However, England under the House of Plantagenet was considerably more powerful than France under the House of Capet. This was particularly true when England added Gascony, Anjou, Aquitaine (basically all of western France) and parts of Ireland, Scotland and Wales, (and allied to Burgundy) to become the Angevin Empire in the 12th century. (Angevin because it was ruled by the royal line of Anjou of whom King Richard the Lionheart was its most famous member). The Capetian Kings of France wouldn’t stand for it and made it their mission over the next 250 years to enlarge the Kingdom of France at the expense of the Angevin Empire and the Kingdom of England. This led to the Hundred Years’ War in the 14th and 15th Centuries.
The first 91 years of the Hundred Years’ War: The naval battle of Sluys, chevauchee, knights, longbows, the Black Prince, the Dauphin, Battle of Crecy, the Black Death, Battle of Portiers, the Black Death, King Henry V, St Crispin’s Day, Battle of Agincourt, and the English declare victory.
The next 21 years: Joan of Arc, Siege of Orleans, The Sudden but Inevitable Betrayal by Burgundy, and the English lose everything except Normandy and a toehold in Gascony.
Toward the end of the war in 1449, King Charles VII of France violated the Treaty of Tours and invaded the last significant English possession on continental Europe, Normandy. The English gathered a small army and in March 1450 crossed the channel. The English army was mostly yeoman archers, which is how they won most of their battles in the last 100 years.
However, this time the French maneuvered them into a position where they could be attacked on three sides, so the English and Welsh bowmen could not concentrate their fire. The low number of heavily armed and armored knights and men-at-arms couldn’t adequately protect the the lightly armored archers. On 15 April 1450, the French knights, professional men at arms, and mercenary companies handily overran the English outside of the town of Formigny, on the road between Caen and Bayeux. As a result of the battle, all of Normandy except Calais would be ceded to the Kingdom of France, and effectively ended the Hundred Years’ War.
The formal peace treaty was not signed for another 20 years, but after the Battle of Formigny, the English no longer sought territorial possessions on the continent and turned their attention to the sea.