(i) Rise of Strong National States.

(ii) Growth of trade industries.

(iii) Money Economy.

(iv) Rise of Capitalism.

(v) Scarcity of labour.

(vi) Crusades.

(vii) Spread of Epidemics.

Detailed Answer : 

The causes for the decline of feudalism are : 

(i) Firstly, feudalism contained in itself the seeds of its destruction. As Henry Martin has observed, “Feudalism concealed in its bosom the weapons with which it would be itself one day smitten”. In course of time, when the feudal lords began to assert themselves too much, the kings who headed the feudal hierarchy, thought of bringing them under control. In this task they received full support from the newly emerged middle classes and freemen who were not under the control of the lords. 

(ii) Secondly, the liberation of the serfs due to enormous growth in trade and commerce also greatly contributed to the decline of feudalism. With the growth of trade and commerce, a number of new cities and towns grew which provided new opportunities for work. The serfs got an opportunity to free themselves of the feudal lords by taking up work in the new towns. It may be observed that according to the existing feudal laws, a serf could become a freeman if he stayed away from the manor for more than one year. 

(iii) Thirdly, the Crusades or the Holy Wars also greatly contributed to the decline of the feudal system. As a result of these wars, the Europeans learnt the use of gun-powder from the Muslims. The discovery of gunpowder greatly undermined the importance of the feudal castles. As a result, it was no more possible for the feudal lords to take shelter in these castles and defy the authority of the king. 

(iv) The Crusades contributed to the decline of feudalism in another way too. They opened up trade between Europe and cities of Constantinople and Alexandria. As a result, commerce and industry in Europe received a fillip and a number of important cities developed. The merchants and artisans residing in these cities wished to free themselves from the control of feudal over-lords. 

(v) Fifthly, the scarcity of labour force in Europe as a result of Black Death (which took a heavy toll of life in Europe) enhanced the bargaining powers of the serfs and rendered feudal system weak.