off the Cotentin Peninsula. An additional three infantry divisions had landed to reinforce the Corps. Major General J. Lawton Collins, the Corps Commander, drove his troops hard, replacing units in the front lines or sacking officers if progress was slow. The Germans facing VII Corps were a mix of regiments and battlegroups from several divisions, many of which had already suffered heavy casualties fighting the American airborne troops in the first days of the landings. Very few German armored or mobile troops could be sent to this part of the front because of the threat to Caen further east. Infantry reinforcements arrived only slowly. Tactically, the Germans' flooding of the Douve worked against them because it secured the Allied southern flank. By 16 June there were no further natural obstacles in front of the American forces. The German command was in some confusion. Erwin Rommel and other commanders wished to withdraw their troops in good order into the Atlantic Wall fortifications of Cherbourg, where they could have withstood a siege for some time. Adolf Hitler demanded that they hold their present lines even though this risked disaster. Late on 17 June Hitler agreed that the troops might withdraw but specified that they were to occupy a new, illogical defensive line, spanning the entire peninsula just south of Cherbourg. Rommel protested against this order, but he nevertheless relieved General Wilhelm Fahrmbacher, commanding the LXXXIV Corps, who he thought was trying to circumvent it. Assault on Cherbourg On 18 June the US 9th Infantry Division reached the west coast of the peninsula, isolating the Cherbourg garrison from any potential reinforcements. Within 24 hours, the 4th Infantry, 9th and 79th Infantry Divisions were driving north on a broad front. There was little opposition on the western side of the peninsula and on the eastern side, and the exhausted defenders around Montebourg collapsed. Several large caches of V-1 flying bombs were discovered by the Americans in addition to a V-2 rocket installation at Brix. In two days, the American divisions were within striking distance of Cherbourg. The garrison commander, Lieutenant General Karl-Wilhelm von Schlieben, had 21,000 men but many of these were hastily drafted naval personnel or from labour units. The fighting troops who had retreated to Cherbourg (including the remnants of von Schlieben's own division, the 709th), were tired and disorganised. Food, fuel and ammunition were short. The Luftwaffe dropped a few supplies,