German wartime officer ranks were permanent, which often made it impossible for German officers to be promoted to the higher rank which their wartime billet would actually have warranted.
Of course, Adolf Hitler could, and did, force promotions of officers and generals he favored, outside of the normal system.
In wartime, promotions could be made — governed by strict regulations — in the following cases:
a) after serving a certain time (and not dependend on billets authorized in KStN), in particular:
c) over authorized strength Kapitulanten to Unteroffizier, Offiziersanwärter to Unteroffizier and Feldwebel;
d) for distinction before the enemy — vor dem Feind — to Gefreiter, Unteroffizier, Feldwebel and Oberfeldwebel;
e) severely wounded;
f) leaving active duty — Beurlaubtenstand — to the next higher rank;
g) killed, in enemy captivity, or missing soldiers.
The usual way of promotion would be Schütze, Gefreiter, Obergefreiter, Unteroffizier, Feldwebel, Oberfeldwebel, Leutnant.
The rank designations Oberschütze, Stabsgefreiter, Unterfeldwebel and Stabsfeldwebel were rewards for long serving soldiers who could not advance further for one reason or another.
Military Personnel Billet Groups, Functions, and Ranks Discussed
Military Personnal Job Descriptions
Military Individual Figure Symbols