The title of dux, given by the Romans to high military commanders with territorial responsibilities, was assumed by the barbarian invaders of the Roman Empire and was used in their kingdoms and also in France and Germany for rulers of very large areas. The early Carolingian sovereigns in France and in Germany continued to appoint dukes, but their weaker successors found themselves increasingly constrained to free the dukes from royal control in the areas that they had to defend.

Franconia, Swabia, Bavaria, and Saxony, originally the homes of distinct tribes, emerged as the great “stemduchies” of Germany when the dukes appointed by the Carolingians as military governors made themselves increasingly independent.

In the 12th century the Hohenstaufen emperors, who created the new duchies of Austria (1156) and Styria (1180), seemed likely to succeed in reducing the dukes to genuinely obedient vassalage. At the same time, the lesser noble families began to consolidate their own holdings and jurisdiction at the expense of the ducal authority. The growth of these smaller territorial principalities (countships, etc.) naturally diminished the real prestige of the dukes. Despite the collapse of the Hohenstaufen design after 1250 and the success of the dukes in securing their independence in their own principalities, their title came no longer to denote greater power under the king but to signify only a higher rank than that of the princely counts. Furthermore, with the extensive privileges accorded the electors (only one of whom was a duke) by the Golden Bull of 1356 (Golden Bull of Emperor Charles IV), the duke had ceased even in theory to be the highest-ranking of the princes of the empire; the Austrian dukes indeed assumed the new title of archduke, claiming equal rights with electors.

From the 16th to the 19th century, lords of even comparatively small territories were granted or took the ducal title. Eleven duchies survived until 1918: Oldenburg, the two Mecklenburgs (east and west), Saxe-Weimar (as the grand duchy of Saxony), Baden, and Hesse-Darmstadt were grand duchies; and Anhalt, Brunswick, Saxe-Altenburg, Saxe-Meiningen, and Saxe-Coburg-Gotha were sovereign duchies.

The dukes of Normandy, Aquitaine, and Burgundy were practically independent of the French crown in the early feudal period, as also was the duke of Brittany, though the French royal chancellery at first accorded him only the style of count. Gradually, however, these great fiefs were reunited to the French crown. Thereafter they were granted only in appanage, as duchés-pairies, or peerage duchies—initially to princes of the blood royal but, from the 16th century onward, also to bastard princes of the blood, to foreign princes, and to other noble subjects of the French king. Duchés-pairies were hereditary, but there were also hereditary duchies that were not peerage titles, as well as life duchies (à brevet, or par lettres). Apart from those in the royal house of France, there were more than 30 ducal titles dating from the ancien régime still being borne (unofficially) in the 1980s, the premier duchy of France being that of Uzès (1565; registered 1572).

The great territorial duchies of Italy that survived into modern times were those of Milan, Florence (as the grand duchy of Tuscany), Lucca, Mantua, Modena, and Parma-Piacenza. The popes, the emperors, and the kings of Naples, however, could all bestow the ducal title as they wished and often did so; consequently, the title is now fairly widespread. The kings of the house of Savoy gave the title of duca occasionally to their offspring.

The Visigothic duchies of Spain disappeared after the Muslim conquest. During the Christian reconquest the title of duque was revived for honorific purposes. Apart from the Castilian duchy of Soria y Molina, created in 1370 for Bertrand du Guesclin (Guesclin, Bertrand du), the title was at first usually reserved for royal princes, but, from the middle of the 15th century onward, it was accorded more and more frequently to other nobles. Of these latter creations, the premier surviving is that of Medina Sidonia (1445). The Spanish kings also created duchies very liberally in their Neapolitan and Sicilian dominions. By virtue of the right accorded to him by the Cortes, General Francisco Franco (Franco, Francisco) created three duchies in 1948: those of Calvo Sotelo, of Mola, and of Primo de Rivera.

John I of Portugal (John I) created the duchies of Coimbra and Viseu for his sons Dom Pedro and Dom Henrique after their capture of Ceuta from the Moors in 1415, and in 1442 he created the duchy of Bragança for his illegitimate son Afonso. Six more duchies were created for branches of the royal house before the Spanish annexation of Portugal. Thereafter duchies were accorded outside the royal house, but the total number of creations was far smaller than in Spain.

There were no English ducal titles (the duchies of Normandy and Aquitaine held by the English kings being, of course, French fiefs) until 1337, when Edward III erected the county of Cornwall into a duchy for his son Edward, the Black Prince. There followed the duchies of Lancaster (1351), Clarence (1362), York (1385), Gloucester (1385), Bedford (1st creation; 1413), and Somerset (1st creation; 1443), all for descendants of the royal house in the male line. In 1444, however, Humphrey Stafford, of royal blood only through his mother, was made Duke of Buckingham (1st creation). After the creation of the dukedom of Norfolk in 1483, the title became increasingly recognized as not being reserved for the royal blood.

In Scotland the title was first bestowed in 1398 by Robert III on his eldest son, David, who was made Duke of Rothesay, and on his brother Robert, Duke of Albany.

In the late 20th century, apart from royal dukedoms, there were nine dukedoms in the peerage of England (Norfolk, 1483; Somerset, 1546; Richmond, 1675; Grafton, 1675; Beaufort, 1682; St. Albans, 1684; Bedford, 1694; Devonshire, 1694; and Rutland, 1703); eight in the peerage of Scotland (Hamilton, 1643; Buccleuch, 1663; Lennox, 1675; Queensberry, 1684; Argyll, 1701; Atholl, 1703; Montrose, 1707; and Roxburghe, 1707); six in the peerage of Great Britain (Marlborough, 1702; Brandon, 1711; Portland, 1716; Manchester, 1719; Newcastle, 1756; and Northumberland, 1766); two in the peerage of Ireland (Leinster, 1766; and Abercorn, 1868); and six in the peerage of the United Kingdom (Wellington, 1814; Sutherland, 1833; Westminster, 1874; Gordon, 1876; Argyll, 1892; and Fife, 1900). However, the Duke of Richmond was also Duke of Lennox and Duke of Gordon; the Duke of Buccleuch was also Duke of Queensberry; the Duke of Hamilton was also Duke of Brandon; and the dukedom of Argyll belonged both to the peerage of Scotland and to the peerage of the United Kingdom. As a result, the 31 ducal titles provided only 26 dukes.