Operationsbefehl Hartmut (literally "Operation Order Hartmut") was the code word to begin German submarine operations during Operation Weserübung - Nazi Germany's invasion of Denmark and Norway. Occasionally these operations are termed Operation Hartmut. The orders involved submarine screening actions for the German invasion fleet and reconnaissance - particularly off Narvik and Trondheim. The orders also resulted in a number of attacks on Allied forces - particularly in or near the fjords of the Norwegian coast.