Given the task definition and input, reply with output. Generate a correct and concise answer for the question based on the words in the context.

Context : ''Karl-Gerat'' (040/041) (German literally ''Karl-device''), also known as Morser Karl, was a World War II German self-propelled siege mortar (Morser) designed and built by Rheinmetall.
Question : What is the war during which Karl-Gerat was in the armed forces?
World War II