County of Apulia and Calabria

The County of Apulia and Calabria, later the Duchy of Apulia and Calabria, was a Norman state founded by William of Hauteville in 1042 in the territories of Gargano, Capitanata, Apulia, Vulture, and most of Campania. It became a duchy when Robert Guiscard was raised to the rank of duke by Pope Nicholas II in 1059.
The duchy was disestablished in 1130 when the last duke of Apulia and Calabria, Roger II of Sicily became King of Sicily. The title of duke was thereafter used intermittently as a title for the heir apparent to the Kingdom of Sicily.
Creation.
Drogo of Hauteville was made "count" of Apulia & Calabria by Emperor Henry III, with territories lost by Guaimario IV of the Principality of Salerno.
William I of Hauteville, who returned in September 1042 in Melfi, was recognized by all the Normans as supreme leader. He turned to Guaimar IV, Lombard, Prince of Salerno, and Rainulf Drengot, Count of Aversa, and offered both an alliance. With the unification of the two Norman families, Altavilla and Drengot, Guaimar offered official recognition of the conquests and at the end of the year, an assembly of Lombards and Norman barons at Melfi met with Rainulf and William, which ended at the beginning of the following year (1043).
In this meeting, Guaimar V of Salerno ensured the Hauteville dominance over Melfi. William of Hauteville formed the second core of his possessions and differentiated himself from Rainulf I of Aversa, head of the territories of Campania. All the barons present offered a tribute as a vassal to Guaimar, which recognized William I of Hauteville as the first of the title of "Count of Apulia". To tie it to himself, he offered to marry her niece Guide, daughter of Guy, Duke of Sorrento. Guaimar reconfirmed the title of count to Rainulf as well, which created the County of Puglia.
Duchy of Apulia and Calabria.
William stated that the first capital of the county, and home of the Crown would be Melfi, a city that would remain outside the partition. It would remain capital for forty years before being moved to Salerno: the center of the city of Melfi was divided into twelve districts, each of them with a palace and a count with control over that area of town.
After 1059 the county was named "Ducato di Puglia e Calabria" ("Duchy of Apulia and Calabria"), because Robert Guiscard was named "Duke" by the Pope Nicholas II.
Salerno was conquered in 1077 by the Normands and since then was no more the capital of the Principality of Salerno: these territories were added to the Duchy of Apulia & Calabria. With this conquest the Normans controlled all continental southern Italy, with the exception of the small Duchy of Naples.
The next year the Duchy's capital was moved from Melfi to Salerno and started to look at the conquest of Sicily: the Normands in this way created the precursor of the Kingdom of Sicily, the first unified state in southern Italy that was founded in 1130.
Salerno remained the capital of this southern Italian political entity for half a century (from 1078 to 1130), when the city flourished with the "Schola Medica Salernitana".
List of counts and dukes.
William is usually considered the first count of Apulia and Calabria. In 1047, the Emperor Henry III of Germany took away Guaimar's ducal title. He christened William's brother and successor Drogo "Dux et Magister Italiae comesque Normannorum totius Apuliae et Calabriae" and made him a direct vassal of the emperor.
In 1127 the duchy passed to the count of Sicily. It was thereafter used intermittently as a title for the heir apparent.
The title was left vacant after the death of Roger IV. It may have been revived for a short-lived son of William II:
It was revived by King Tancred for his eldest son in 1189: