In developing plans for the Allied invasion of France, from the very beginning, SHAEF planners considered the vital need to secure deepwater ports to bring in all the supplies needed to support an army of hundreds of thousands of troops. Cherbourg, at the tip of the Cotentin Peninsula, was the closest to the landing beaches chosen for Operation ‘Overlord’. The planners therefore decided to land forces at the base on the peninsula, in order to enable the rapid capture of Cherbourg, and also to widen the front of the landing. The First US Army was tasked to capture it as quickly as possible. In the early hours of June 6, paratroopers from the 82nd and 101st Airborne Divisions landed inland from Utah Beach to capture the beach exits, and secure the crossings over the Douve River at Carentan. On June 10, the 101st Airborne Division captured Carentan, thus liaising with the Omaha beachhead and ensuring the Allies a continuous front.

This success allowed VII Corps to advance westward to isolate the Cotentin Peninsula. On June 18, the 9th Infantry Division reached the west coast of the peninsula, and within 24 hours, the 4th, 9th, and 79th Infantry Divisions advanced northward. Within two days, they were within striking distance of Cherbourg, but the German commander, Generalleutnant Karl-Wilhelm von Schlieben, rejected a summons to surrender and began demolitions of the port. The VII Corps launched a general assault on June 22. Resistance was initially strong, but the Americans gradually drove the German defenders from their bunkers and pillboxes. Allied warships and cruisers bombarded the defences on the 25th, and the 79th Division captured Fort du Roule, which dominated Cherbourg and its defences, on the 26th. General von Schlieben surrendered the same day, and the port and arsenal capitulated on the 27th. Fregattenkapitän Witt, the port commander, escaped by boat to the Fort de l’Ouest, a bastion on the breakwater, and took command of the small forces holding this fort and the Fort du Centre. After two days of artillery hammering and several bombing raids, the two strongholds surrendered on June 29.

The Battle of Cherbourg was over. In the battle for the Cotentin and Cherbourg, VII Corps had suffered over 22,000 casualties, while the Germans had lost 39,000 men taken prisoner, in addition to an unknown number killed. The early capture of Cherbourg was a major defeat for the Germans. In their plan to deny the Allies access to French ports, the German high command had anticipated that Cherbourg could hold out for several weeks (as Brest was soon to do). The capitulation of the Festung came much earlier than expected, and Hitler’s inner circle considered the fortress’s commander, General von Schlieben, a very poor commander. However, his engineers had carried out intensive demolition of the port, which was so thoroughly destroyed and mined that it was only put back into very limited use by mid-August.