I have heard a bit of German family lore from the war and I am wondering how historically plausible it is. My partner's grandfather was said to have wanted to be a teacher when the war started but was conscripted and assigned to a U-boat in the Mediterranean. He then survived the war by being captured and brought to Egypt as a POW. However, this seemed odd to me with the particularly voluntary nature of modern submarine services. Were there conscripted soldiers assigned to submarines in the German Navy? Is this a plausible thing that could have happened?