I was recently promoted to leader of my legion, and it opened up new options for me which was kind of exciting...

It got me thinking that it would be neat if there were military ranks inside the legion. Everyone would start out as a private except the founder of the legion who would be the supreme commander, etc.

As people prove themselves, they would advance through the ranks based on the recommendations of some percentage of those above them. Higher ranks would have some kind of additional privledges.

There could be some kind of bonus paid to the legion. The total amount would be based on the total strength of the legion, and the split would be a weighted percentage of a person's rank versus the rest of the ranks in the legion. The bonus could be a credit bonus, attack bonus, mineral bonus, etc.

Some ideas to member ranks:
Admiral
Commander
Captain
Officer
Ensign

I dont think navy ranks would be appropriate since all of us are captains of our own ships. There should be other ranks that are more appropriate than the common navy ranks.. just a thought.

Not all captains are of the rank Captain. Trust me, its what I do for a living, some Commanding Officers are Leiutenants, some Leiutenant Commanders, Commanders, Captains, even Admirals sometimes are the Commanding Officer for some commands.

Yes but no matter what their rank, if they are in charge of the ship, they get to be called "Captain".

You could just start the ranks at captain...