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Some reasons for the decline of Feudal Europe:

The Crusades and travel during the Middle Ages opened new trade options to England

England started to move from land based economy to a money based economy

The Black Death - this reduced the population of England by one third. Labour became a valuable commodity

The Peasants Revolt - Peasants realised their worth and demanded changes. Charters were granted but ignored by nobles

More trade saw the growth of more towns

Peasants moved away from the country into towns they were eventually allowed to buy their freedom

Land was rented and the rights of lords over labour decreased

The Feudal Levy was unpopular and as time went by Nobles preferred to pay the King rather than to fight and raise troops

Armed men were paid a wage and Medieval warfare was financed by taxes and loans

Nobles became much weaker

A centralized government was established