How did the threat of invasion lead to the sever of the manor system?

The manor system offered people protection.

In the manor system, peasants will be allowed to work in a land that belonged to the certain lord and require the peasants to make some contributions from the result of their works.

As a return, the Lord will provide knights to protect everyone that live in that land, including the peasants.

Idon’t know i’m doing this for points

Bis your correct answer