As a result of the powerful American defense to the north and east, XLVII Panzer Corps commander Gen. von Lüttwitz decided to encircle Bastogne and strike from the south and southwest, beginning the night of 20/21 December. German Panzer reconnaissance units had initial success, nearly overrunning the American artillery positions southwest of Bastogne before being stopped by a makeshift force. All seven highways leading to Bastogne were cut by German forces by noon on 21 December, and by nightfall the conglomeration of airborne and armored infantry forces were recognized by both sides as being surrounded.