How did Rome's military conquests create strains on the military?

Below are the following reasons:

1. The Kingdom get larger in size its borderline was more enlarged and became hard to defend

2. There was a refusal to accept or comply the occupation in other places, requesting an enduring military presence

3. Rome was obligated to enlist more soldiers from the savage tribes beyond its boundaries just to address the problems.

4. This recruitment showing the armed forces to Roman military technology and association, to its political institutions, and to the material richness of the Roman heartland.

5. The society organizes itself for military conflict and violence of the Empire that gave the soldiery the power to form their own rulers by electing military officers to the seat of power. The outcome was a series of civil wars

6. Retired soldiers are settled within Rome’s borderline

7. During 4th century, there are vast Hunnish immigrants from the east. These hostile tribes caused a great displacement of real German people to the west and south into Rome's Kingdom. The former soldiers became an aid in the German capture. The result was the termination of the Western Territory.