The First Battle of Smolensk was the first major battle during Operation Barbarossa in World War II that significantly delayed the advance of Hitler's Wehrmacht in the USSR. It took place in the region around the city of Smolensk between July 10 and September 10, 1941, i.e., it raged for two full months about 400 km west of Moscow. At that point the Wehrmacht had advanced 500 km into the USSR without major difficulties in the mere 18 days that had elapsed since the initial invasion of June 22, 1941.