During the Second World War (1939–1945), the German Army occupied the north of France and fortified the coastline against invasion. As a deep-water port, Cherbourg was of strategic importance, very heavily protected against seaborne assault.
The Germans arrived on the outskirts of Cherbourg on 17 June 1940, towards the end of the Battle of France. The 19, the City Council declared the city open, and Generalmajor Erwin Rommel, commander of the 7th Panzer Division, received the surrender of the city from the hands of the maritime prefect, Vice-Admiral Jules Le Bigot (fr), who had earlier destroyed submarines under construction at the arsenal and East Fort.
Four years later, Cherbourg, the only deep-water port in the region, was the primary objective of the American troops who had landed at Utah Beach during the Battle of Normandy. The Battle of Cherbourg was required to give the Allies a point of logistic support for human resupply and material of the troops. American troops encircled the city on 21 June 1944. At the end of furious street fighting and bitter resistance from the Fort du Roule, Generalleutnant Karl-Wilhelm von Schlieben, Konteradmiral Walter Hennecke and 37,000 German soldiers surrendered on 26 June to Major General Joseph Lawton Collins, Commanding General (CG) of the U.S. VII Corps. After a month of demining and repairs by American and French engineers, the port, completely razed by the Germans and the bombing, welcomed the first Liberty ships and became, until the victory of 1945, the largest port in the world, with traffic double that of New York. It was also the endpoint of the gasoline which crossed the English Channel via the underwater pipeline PLUTO (Pipe Line Under The Ocean), and the starting point of the Red Ball Express, truck transport circuit to Chartres.
Cherbourg was returned to France by the Americans on 14 October 1945. It was cited in the Order of the Army on 2 June 1948 and received the Croix de guerre with Palm.