 Complete the following phrase:  The K 39 and its variants served as mobile artillery only with Artillery Battalions Artillerie-Abteilungen 767 and 768, each battalion being organized with 3 batteries, each with two guns. Both battalions were raised in AprilMay 1940, but it is unknown if either participated in the Battle of France. For Operation Barbarossa 767 was assigned to the Sixth Army of Army Group South where it participated in the sieges of 