During the Hundred Years' war there was a big Decline of Feudalism. A big shift of power occured from 1337-1453.
Where are my taxes. I need to supply my own army.
The war had started in 1337 when English kings had claimed land in France. The French kings had believed that the land was their own. This led to confict between both countries.
This conflict was the reason for the war. This is when feudalism had started to disappear and slowly die. This was caused by how the kings ruled during that time.
For our country
The kings had started to collect high taxes from the common people. With these taxes the kings started to supply their own armies.
This contributed to the decline of feudalism by having the classes mixed up. Certain roles have shifted to other people. For example, the nobleman lost a certain amount of power because the kings didn't need them for thir armies. The kings started to rely on the soldiers instead.
This meant that Kings and the common people had gotten more power during this time. Since the kings had paid the armies to fight for them, there had started to be nationalism. The Knights had started to feel proud for fighting for their country. This made most knights have more important jobs than some lords.