Ranks used on the server

UNSC Marine Corps Ranking Structure
Enlisted Ranks
Private-PVT
Private First Class-PFC
Specialist-SPC
Corporal-CPL
Non Commissioned Officers
Sergeant-SGT
Staff Sergeant-SSGT
Sergeant First Class-SFC
Senior Non Commissioned Officers
Master Sergeant-MSGT
First Sergeant-FSGT
Master Gunnery Sergeant-MGSGT
Sergeant Major of the Marine Corps-SGMMC
Warrant Officers
Warrant Officer-WO
Chief Warrant Officer 2-CWO2
Chief Warrant Officer 3-CWO3
Chief Warrant Officer 4-CWO4
Chief Warrant Officer 5-CWO5
Commissioned Officers
Second Lieutenant-2LT
Lieutenant-LT
First Lieutenant-1LT
Captain-CPT
Staff Captain-SCPT
Major-MAJ
Field Major-FMAJ
Senior Comissioned Officers
Commander
Strike Commander-SCOM
Lieutenant Colonel-LTCOL
Colonel-COL
Force Colonel-FCOL
Brigadier-BRIG
Generals
Brigadier General-BG
Major General-MG
General-GEN
Captain General-CGEN(Captain General is the highest obtainable rank, whereas Field Marshal is the highest rank but can't be obtained)
Field Marshal

UNSC Army Ranking Structure
Enlisted Ranks
Private-PVT
Private First Class-PFC
Specialist-SPC
Corporal-CPL
Non Comissioned Officers
Sergeant-SGT
Staff Sergeant-SSGT
Senior Non Commissioned Officers
Gunnery Sergeant-GSGT
First Sergeant-FSGT
Sergeant Major-SGM
Command Sergeant Major-CSGM
Sergeant Major of the Army-SMTA
Warrant Officers
Warrant Officer-WO
Chief Warrant Officer 2-CWO2
Chief Warrant Officer 3-CWO3
Chief Warrant Officer 4-CWO4
Chief Warrant Officer 5-CWO5
Commissioned Officers
Second Lieutenant-2LT
Lieutenant-LT
First Lieutenant-1LT
Captain-CPT
Staff Captain-SCPT
Major-MAJ
Field Major-FMAJ
Senior Comissioned Officers
Commander
Strike Commander-SCOM
Lieutenant Colonel-LTCOL
Colonel-COL
Force Colonel-FCOL
Brigadier-BRIG
Generals
Brigadier General-BG
Major General-MG
General-GEN
Captain General-CGEN(Captain General is the highest obtainable rank, whereas Field Marshal is the highest rank but can't be obtained)
Field Marshal

UNSC Navy Ranking Structure
Enlisted Ranks
Seaman Recruit-SR
Seaman Apprentice-SA
Seaman-SN
Non Comissioned Officers
Petty Officer Third Class-PO3
Petty Officer Second Class-PO2
Petty Officer First Class-PO1
Chief Petty Officer-CPO
Senior Non Commissioned Officers
Senior Chief Petty Officer-SCPO
Master Chief Petty Officer-MCPO
Command Master Chief Petty Officer-CMCPO
Fleet Master Chief Petty Officer-FMCPO
Master Chief Petty Officer of the Navy-MCPON
Warrant Officers
Warrant Officer-WO
Chief Warrant Officer 2-CWO2
Chief Warrant Officer 3-CWO3
Chief Warrant Officer 4-CWO4
Chief Warrant Officer 5-CWO5
Commissioned Officers
Ensign-EN
Lieutenant Junior Grade-LTJG
Sub Lieutenant-SLT
Lieutenant Commander-LTCOM
Commander
Captain
Commodore
Admirals
Rear Admiral(Lower Half)RDML
Rear Admiral(Upper Half)RADM
Vice Admiral-VADM
Admiral-ADM
Fleet Admiral-FADM(Field Marshal is the highest rank of the server
Field Marshal

UNSC Air-Force Ranking Structure
Enlisted
Airman Basic-AB
Airman-Amn
Airman First Class-AFC
Senior Airman-SNA
Non Commissioned Officers
Sergeant-SGT
Staff Sergeant-SSGT
Technical Sergeant-TSGT
Senior Non Commissioned Officers
Master Sergeant-MSGT
Senior Master Sergeant-SMSGT
Chief Master Sergeant-CMSGT
Command Chief Master Sergeant-CCMSGT
Warrant Officers
Warrant Officer-WO
Warrant Officer 2-WO2
Warrant Officer 3-WO3
Warrant Officer 4-WO4
Chief Warrant Officer 5-CWO5
Commissioned Officers
Officer Cadet-OC
Acting Pilot Officer-APO
Pilot Officer-PO
Flying Officer-FO
Flying Lieutenant-FL
Senior Commissioned Officers
Squadron Leader-SL
Wing Commander-WCOM
Group Captain-GCPT
Air Commodore
Marshals/General Type Ranks
Air Vice Marshal-AVM
Air Marshal-AM
Air Chief Marshal-ACM
Marshal of the Air Force(Highest Air Force Rank)
Field Marshal

UNSC Spartan Contingent Ranking Structure

Enlisted
Recruit-RCT
Private-PVT
Private First Class-PFC
Lance Corporal-LCPL
Non Commissioned Officers
Sergeant-SGT
Staff Sergeant-SSGT
Gunnery Sergeant-GSGT
Master Sergeant-MSGT
Sergeant First Class-SFC
Senior Master Sergeant-SMSGT
First Sergeant-FSGT
Sergeant Major-SGM
Senior Non Commissioned Officers
Company Sergeant Major-CNSGM
Chief Master Sergeant-CMSGT
Master Gunnery Sergeant-MGSGT
Regimental Sergeant Major-RSGM
Command Sergeant
Major-CMSGM
Command Chief Master Sergeant-CCMSGT
Warrant Officers
Warrant Officer-WO
Warrant Officer 2-WO2
Warrant Officer 3-WO3
Warrant Officer 4-WO4
Chief Warrant Officer 5-CWO
Commissioned Officers
Second Lieutenant-2LT
Lieutenant-LT
First Lieutenant-1LT
Captain-CPT
Group Captain-GCPT
Staff Captain-SCPT
Major-MAJ
Field Major-FMAJ
Lieutenant Colonel-LTCOL
Colonel-COL
Senior Commissioned Officers
Lieutenant Commander-LTCOM
Commander
Strike Commander-SCOM
Brigadier-BRIG
Generals
Brigadier General-BG
Major General-MG
Lieutenant General-LG
General-GEN
Captain General-CGEN
Field Marshal

Swords of Sangheilios Ranking Structure
Enlisted
Minor
Major
Ultra
General
Spec Ops
Spec Ops Minor
Spec Ops
Ranger
Spec Ops Officer
Higher Command
Zealot
Elite Field Marshal(Not the Field Marshal of the UNSC-Is a lower rank)
Ship Master
Fleet Master
Supreme Commander
High Admiral
Arbiter
Field Marshal(UNSC Version is Higher than Arbiter command wise)