For most military matters, Congress has the final say. The president does have executive order over some things, and there are certain ways that the president can get around the power of congress in some matters.
The final authority over what? The answer to this question depends on the subject under discussion.
when military authority takes priority over an event on a military installion or an offense by a member of the military
Who had the final authority over the colonists, royal governors, colonial legislatures, citizens themselves, the English monarch
your family
hell no
As the Commander in Chief the US President has authority over the entire military, so all of them. He has the authority to deploy up to 400,000 at a time without needing the approval of Congress
The countries Minister of defence
It was the final act that abolished slavery,and said that congress had final authority over states.
Martial Law .
It depends which country you are referring to.
IRS
it represents the commander's power and authority over his indidual unit