Article snapshot taken from Wikipedia with creative commons attribution-sharealike license.
Give it a read and then ask your questions in the chat.
We can research this topic together.
XVIII. Armeekorps was formed in Salzburg, Austria, on 1 April 1938, following the Anschluss of Austria into the German Reich. During the life of the XVIII. Armeekorps, they took part in the Polish campaign, Fall Weiss, and the campaign in the West 1940 (Fall Gelb and Fall Rot), and performed occupation duties in France. On 30 October 1940, the Corps gave up some elements to newly forming XXXXIX. Gebirgskorps, and on 1 November, they re-designated the Korps name to XVIII. Gebirgskorps, under which it participated to Operation Marita, the invasion of Greece in spring 1941.
Germany