Answer :

The highest rank in the military is a general.
But there are five general ranks:

1. Brigadier general
2. Major general
3. Lieutenant general
4. General of generals? Or more know as the chief of staff (In U.S military)
5. Is the General of the army which is reserved only for wartime
-Fleet Admiral for Navy
-General of the Airforce
-4 star general for Marines
But the Chief of Staff is the highest among them

So in peacetime, the highest rank is the Chief of Staff which is in control of the entire military and is in the Presidents inner circle (In U.S military)

The reason why I used the U.S is because they have the strongest, most trained, experienced, well equipped military in the world so this makes the Chief of Staff the most powerful military commander in the world.

Answer:

Army: General of the army, Navy: Fleet adm. Air force 5 star general

Explanation: