Cherbourg-Octeville is a city and commune, situated on the Cotentin peninsula in the Manche department of Lower Normandy in north-western France. It is a subprefecture of its department, and was officially formed when the commune of Cherbourg absorbed Octeville on 28 February 2000. Due to its union, it is the most populated city in its department and the second-most in the region after the prefecture, Caen. Cherbourg holds an arsenal of the French Navy. It is also a ferryport, with lines to the English ports of Poole and Portsmouth and St Helier on Jersey.