How did the threat of invasion lead to the development of the manor system? the manor system created a strong military. the manor system offered people protection. the manor system stopped invaders from entering europe. the manor system kept lords wealthy and powerful.

The answer to this question is 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.