Duke is a European title. It comes from the Latin word dux (leader) and is the title next highest to prince. In England, there are few dukes outside the royal family, where the sons have the title of Royal Duke. The wife of a duke is a duchess, the oldest son is a lord with the rank of marquess, and younger sons and daughters are called lords and ladies.
In early days, a duke was a leader in battle and sometimes a ruler as well. The first English duke was the Black Prince, oldest son of Edward III, who was made Duke of Cornwall in 1337. Archduke was a title used by members of the royal family of Habsburg from 1453 until the end of World War I (1914-1918).
