Rank theme "Deutschland"; typos and missing/corrected abbreviations:
Admiral (ADM)
Vizeadmiral (VADM)
Konteradmiral (KADM)
Flottillenadmiral (FADM)
Kapitän zur See (KZS)
Fregattenkapitän (FK)
Korvettenkapitän (KK)
General (GEN)
Generalleutnant (GL)
Generalmajor (GM)
Brigadegeneral (BG)
Oberst (O)
Oberstleutnant (OTL)
Major (M)
These are all from the Bundeswehr. Previous ranks were kind of mixed from multiple eras (Kommodore ceased to exist after WWII and Brigadegeneral didn't exist before that). If you wanted to represent another era, just say so. Personally I'm going for a WWI'ish theme, with one extra rank for each branch, so I could probably provide more themes.