Explain how tyranny might result when the military is not kept under civilian control

If the military is not kept under civilian control, it may choose to take up the governance in its own hands and the leaders of the military might turn authoritarians.

Explanation:

Given the fact that the military has direct access to all the weapons of mass destruction and also has highly trained troops of efficient men, it can threaten the civilian leaders running a democratic government of its in order to take the leadership of the nation in its own hands.

This might bring an end to the democratic way of functioning and the common public of the nation would be in great distress.