Walter Karl Gustav August Ernst von Reichenau was a German Generalfeldmarschall in the Heer (Army) of Nazi Germany during World War II. He was nicknamed "The Bull". Reichenau commanded the 6th Army during the invasions of Belgium and France. During Operation Barbarossa, the invasion of the Soviet Union, he continued to command the 6th Army as part of Army Group South as it captured Ukraine and advanced deep into the USSR.