That King Phillip VI, he thinks he can take the duchy just because I won't acknowledge my allegiance to France? Oh I'll show him!
And so, King Edward III led his troops to France and won battles taking control of Auberoche, Crecy, and Calais starting the 100 year war.
He is not coming sire.
Peace lasted a decade until Edward's son, Edward IV, refused demands to come to Paris to meet with king Charles V who wanted to take back land that England had taken from them years ago. Edward died and his son Richard II claimed control making peace with France in 1389 lasting about 25 years.
Not coming? NOT COMING! THEN WE SHALL TAKE THE LAND BY FORCE! ASSEMBLE MY ARMY
In 1415 King Henry V invaded Normandy. When he died, his brother John deep military campaigns into France. He was crowned in France and afterwards Charles VII was crowned as king in Notre Dame. Eventually the English were pushed back by people like Joan of Arc.
Joan of Arc was a legendary French Hero. She was born a peasant but claimed to be following God's calling as she led the French To many victories near the end of the war. Eventually she was sold to the English, and was put on trial and burned to the stake at the age of 19.
One development during the 100 years war was the increased sense of national pride among both English and French people. Though the war was initially about family dynasties and the French throne, nationalism played a major role in the conflict and increased after the war.
The 100 years war lead to fundamental changes in warfare. The use of knights and cavalry was proven to be too expensive to sustain. English longbows were able to pierce through the armor of knights. Also, armies seemed to be mostly made up of peasants.