The following list includes the battalion's Rank Structure (from high to low). Your character's initial rank is determined by your recruitment meeting with the Commander or First Blade.
Ranks:
Commander
First Sword (Second in Command)
Shrike (Tactical Officer)
Captain (Corps Commander)
Adjutant
Quartermaster
Talon (Company commander)
Falcon (Talon's Aide/Specialty field)
Hawk (Platoon commander)
Raven (Squadron commander)
Blade (Enlisted personnel)
Promotions:
Promotions are earned ICly: any officer can nominate you for a rank up to one less step than their own, but the promotion -must- be approved by the Commander or First Sword. You normally can't be promoted for more than one rank at a time (i.e., a promotion from Blade to Talon). Truly heroic or unusual circumstances are definitely an exception.