A duchy, also called a dukedom, is a country, territory, fief, or domain ruled by a duke or duchess. In Western European tradition, the title of duke ranked among the highest nobility, generally just below the monarch and above counts or earls. Historically, there was a significant distinction between sovereign dukes, who ruled independent states, and dukes who were simply noblemen within larger kingdoms. Some duchies functioned as sovereign states in regions that only later became unified nation‑states, such as Germany (once the Holy Roman Empire, a federal empire) and Italy (later a unified kingdom). By contrast, other duchies were subordinate territories within kingdoms that had already consolidated, either partially or fully, during the medieval era: examples include France, Spain, Sicily, Naples, and the Papal States. Examples In France, several duchies existed in the medieval period, including Normandy, Burgundy, Brittany, and Aquitaine. The medieval German st ...

Duke is a male title either of a monarch ruling over a duchy, or of a member of royalty, or nobility. As rulers, dukes are ranked below emperors, kings, grand princes, grand dukes, and above sovereign princes. As royalty or nobility, they are ranked below grand dukes and above or below princes, depending on the country or specific title. The title comes from French ''duc'', itself from the Latin '' dux'', 'leader', a term used in republican Rome to refer to a military commander without an official rank, and later coming to mean the leading military commander of a province. In most countries, the word ''duchess'' is the female equivalent. Following the reforms of the emperor Diocletian (which separated the civilian and military administrations of the Roman provinces), a ''dux'' became the military commander in each province. The title ''dux'', Hellenised to ''doux'', survived in the Eastern Roman Empire where it continued in several contexts, signifying a rank equivalent ...

Lancashire ( , ; abbreviated ''Lancs'') is a ceremonial county in North West England. It is bordered by Cumbria to the north, North Yorkshire and West Yorkshire to the east, Greater Manchester and Merseyside to the south, and the Irish Sea to the west. The largest settlement is the city of Preston. The county has an area of and had an estimated population of in . Preston and Blackburn are near the centre of the county, Burnley is in the east, the seaside resort of Blackpool on the coast in the west, and the city of Lancaster in the north. For local government purposes the county comprises a non-metropolitan county, with twelve districts, and two unitary authority areas: Blackburn with Darwen and Blackpool. Lancashire County Council and the two unitary councils collaborate through the Lancashire Combined County Authority. The county historically included the Furness and Cartmel peninsulas of Cumbria, northern Greater Manchester and Merseyside, and Warri ...

Cornwall (; or ) is a ceremonial county in South West England. It is one of the Celtic nations and the homeland of the Cornish people. The county is bordered by the Atlantic Ocean to the north and west, Devon to the east, and the English Channel to the south. The largest urban area is the Redruth and Camborne conurbation. The county is predominantly rural, with an area of and an estimated population of in . The county's major settlements include the city of Truro and St Austell in the centre, Redruth and Camborne adjacent to each other in the southwest, Saltash in the extreme southeast, and Penzance and Falmouth on the southern coast. For local government purposes most of Cornwall is a unitary authority area, with the Isles of Scilly governed by a unique local authority. The Cornish nationalist movement disputes the constitutional status of Cornwall and seeks greater autonomy within the United Kingdom. Cornwall is the westernmost part of the South Wes ...