EarthForce ranks, positions and titles: Admiral

Staff/Flag officers:
Admiral
Vice Admiral
Rear Admiral
Colonel
Lieutenant Colonel
Line officers:
Major
Commander
Lieutenant Commander
Lieutenant
Lieutenant (junior grade)
Ensign

The six branches of the service, each headed by one of the Joint Chiefs (who each hold the rank of Admiral) are:
Command (referring to installations and infantry divisions)
Fleet/Navy
Medical Corps
Security
Psi Corps*
and Earth Alliance Special Intelligence Division*

I am assuming that the  rank of 'Captain' is a position reserved for commanders of warships and that
a 'Captain' may have any rank between 'Lieutenant Commander' and 'Colonel ' as Captains are portrayed commanding entire fleets of warships and support vessels and the only officers referred to by that rank are serving or ex-serving starship captains.
So, a former starship captain would retain the title until promoted e.g. Captain then Colonel Lochley.

For the line ranks I have used modern navy ranks but replaced 'Captain' with 'Major' as this appears to be the original intention of the producers of Babylon 5, plus officers with the rank of 'Major' are shown holding important posts. Note: Ensigns seem to wear the same or similar uniforms as the enlisted personnel, except when serving in command and control.



Field officers: in the field the positions of 'Major General' and 'Brigadier General' are occupied below the position of Lieutenant General (rank: Rear Admiral) by promoted Colonels and Lieutenant Colonels respectively, similar to the positions in the modern British Army of Regimental Sergeant Major and  Sergeant Major, held by Warrant Officers class One and Two.



*these specific divisions are mentioned alongside the existence of the Joint Chiefs of Staff but other EartForce officers are generally in the same chain of command

An alternate ranking system:
General (one to five star)
Colonel
Lieutenant Colonel
Major
Captain
Lieutenant Commander**
Lieutenant
Ensign

**there being no official rank of commander because in the cast list for the pilot no rank is given for "Commander" Sinclair and in later seasons Ivanova is always a Lieutenant Commander