These are the ranks used in Call of Duty 4:

Private First Class I
Private First Class II
Lance Corporal
Lance Corporal I
Lance Corporal II
Corporal
Corporal I
Corporal II
Sergeant
Sergeant I
Sergeant II
Staff Sergeant
Staff Sergeant I
Staff Sergeant II
Gunnery Sergeant
Gunnery Sergeant I
Gunnery Sergeant II
Master Sergeant
Master Sergeant I
Master Sergeant II
Master Gunnery Sergeant
Master Gunnery Sergeant I
Master Gunnery Sergeant II
2nd Lieutenant
2nd Lieutenant I
2nd Lieutenant II
1st Lieutenant
1st Lieutenant I
1st Lieutenant II
Captain Captain I
Captain II
Major
Major I
Major II
Lt. Colonel
Lt. Colonel I
Lt. Colonel II
Colonel
Colonel I
Colonel II
Brigadier General
Brigadier General I
Brigadier General II
Major General
Major General I
Major General II
Lieutenant General
Lieutenant General I
Lieutenant General II
General General I
General II
Commander