Tyrrhenian duchies

The Tyrrhenian Duchies are civil and military administrative divisions from the second half of the first millennium, originally dependent on the Byzantine Empire and governed by a military governor (dux). As in other Byzantine territories in Italy, the local nobility succeeded in transforming these duchies into autonomous states, only formally dependent on Constantinople. The principal of these states, which lasted more than five centuries, is the Duchy of Naples.

The Tyrrhenian Duchies each occupied a narrow coastal strip distributed between the south of present-day Lazio and the north of Campania up to the Amalfi Peninsula. From north to south, we find^[1]:

• The Duchy of Gaeta, centered on the city of Gaeta and extending to the city of Fondi to the west and the Garigliano river and Traetto to the east.
• The Duchy of Naples, centered on the city of Naples and including the islands of Ischia and Procida, as well as Capri for a time before it passed to Amalfi, the coast from Pozzuoli to Castellammare di Stabia, and the region of Aversa, a buffer zone with the Principality of Capua.
• The Duchy of Sorrento, which included the northern coast of the Amalfi Peninsula.
• The Duchy of Amalfi, which included the Amalfi Peninsula up to Atrani, as well as the island of Capri from the 9th century.

The major inland cities of the Neapolitan hinterland, such as Sarno, Nocera, or Nola, always remained outside the authority of the Tyrrhenian dukes and depended on the Lombard princes of Capua or Salerno, forming an important communication route between the two principalities^[2]. The Tyrrhenian Duchies, despite regular matrimonial alliances between the Lombard and Neapolitan or Gaetan dynasties, maintained very conflictual relations with these Lombard principalities for most of their existence.

Although the genetic contributions of the Lombards or Byzantines were extremely limited in the Mezzogiorno, medieval peoples primarily defined their ethnicity by the law with which they governed their society^[3]. Thus, in southern Italy at the end of the first millennium, three populations considered themselves distinct.

First, the populations under Lombard law, who inhabited almost the entire southern peninsula, including most of Byzantine Apulia. Then, the populations under Byzantine law, who occupied Salento, Calabria, and Sicily until its invasion by Muslims during the 9th century^[4]. Finally, the populations of the Tyrrhenian Duchies.

These Tyrrhenian populations distinguished themselves from their neighbors by the archaic and particular nature of their law, described as Roman^[5]. In reality, it was the Justinian Code in its 6th-century form, preserved from most subsequent Byzantine legislative innovations. Their particularism did not stop there, as, unlike the overwhelming majority of populations under Byzantine suzerainty, they practiced and administered in Latin rather than Greek. Religiously, despite significant local growth of Greek monasticism, they remained within the Roman and papal orbit, despite the rupture between the Papacy and Constantinople following the Iconoclastic Controversy^[6]. Moreover, the Lombard principalities were not urban states, and the ancient metropolises were gradually abandoned in favor of small rural settlements. The Byzantines, on the other hand, preferred to develop new urban centers rather than rely on and repopulate ancient cities. In this context, the ancient metropolis of Naples, with its 30 to 35,000 inhabitants in the 8th and 9th centuries, was one of the most populous cities in the West. Furthermore, by maintaining its local senate and urban cultural life, albeit diminished but resolutely active, it stood as an anachronism.

The Lombard chroniclers of Monte Cassino clearly distinguished them from populations under more direct Byzantine suzerainty, calling them Quirites^[3]. The populations of the Duchy of Naples thus constituted, along with Venice, the last remnants of the late antique Roman populations.

Following the ephemeral kingdoms of Odoacer (476-493) and the Ostrogoths (493-536), the entire Italian Peninsula returned to Roman suzerainty after the Gothic War led by Emperor Justinian. This reconquest was temporary, however, as the depopulated and ruined territory after 20 years of war was unable to resist the Lombard invasions that began in the late 6th century^[7]. The Mezzogiorno was occupied almost in its entirety in the early years of the 7th century, limiting imperial authority to the Exarchate of Ravenna, Apulia, Calabria, Sicily, and the Duchy of Naples (which at the time included the other Tyrrhenian Duchies, which only gained independence in the 9th century)^[8].

The latter was probably created at this time on the initiative of Pope Gregory the Great^[8], but remained a temporary office extended to all of Campania under the authority of the Exarch of Ravenna^[9]. It was only in 661, during the reign of Constans II, who attempted to drive the Lombards out of southern Italy during a military campaign^[7], that Naples was granted a local dux to better counter Lombard advances in the region. The Lombards remained the dukes' main adversaries for centuries to come^[10].

The 8th century brought changes to the Italian Peninsula that affected the Duchy of Naples. Occupied by its conflicts against the Arabs and Slavs, the Roman Empire was unable to assist its Italian possessions, and Ravenna and its exarchate fell into Lombard hands. The Pope, no longer able to rely on Constantinople, turned to the Franks, who defeated and annexed the Lombard Kingdom before definitively breaking with Constantinople, which was in the midst of the Iconoclastic Controversy, by crowning Charlemagne Emperor. The Lombards, for their part, retreated to the Duchy of Benevento, which they transformed into a principality and aspired to make a second Pavia, their former capital.

In this context, the Duchy of Naples took advantage of the situation to assert its autonomy. Fluctuating its allegiance between the Papacy, the Carolingian Empire, and the Byzantine Empire, depending on the periods of power and crisis of each of these states, the Neapolitan Duchy managed to free itself from direct control by Constantinople^[11], whose tutelage it would only accept when forced^[12]. As early as 763, it chose to place itself under papal suzerainty, better able to support it against the Lombards than distant Constantinople. Obedience to imperial directives became fluctuating, as illustrated by the refusal of Duke Anthimus of Naples to participate in the expedition of Leo V the Armenian against the Saracens in Sicily^[13], or the replacement of Greek and the Emperor's face with Latin and the effigy of San Gennaro, the patron saint of the city, on the coins minted in Naples. It was during this period that the Duchies of Gaeta and Amalfi, hitherto fiefs of the Duchy of Naples, gained their respective independences from the Parthenopean city, taking advantage of Naples' independence to place themselves directly under imperial authority^[14]. This marked the gradual shift of power from the ancient metropolis to these new wealthy port and trading cities during the mid-9th century. Sorrento, however, remained a Neapolitan fief, governed by a prefect, until 1027^[15].

This decline in Byzantine influence allowed for the patrimonialization of the duchies. As early as 840, Duke Sergius I established the heredity of the Dux office, previously theoretically a simple imperial official, and installed his Sergi dynasty, which ruled the duchy until 1137. Under the reign of Duke-Bishop Athanasius II, the Duchy of Naples reached its peak, able to stand up to both the Pope and the Byzantine Empire and to keep the Lombards of Capua in check. The Docibili ducal dynasty also settled in Gaeta^[16][17], while Amalfi retained an electoral system. It was also during this time that Amalfi emerged as the first great Italian merchant republic, before Venice or Genoa, and that the Amalfian Laws were written, a collection of laws and maritime regulations that served as the basis for commercial and navigational jurisprudence throughout the Mediterranean until the 16th century.

These de facto independences did not prevent the Tyrrhenian Duchies from actively collaborating when their interests converged. Thus, when the Lombard prince Sicard of Benevento, the last sovereign of a unified minor Lombardy dreaming of ruling all of southern Italy, took Amalfi in 838 and attacked Sorrento the following year, Naples came to the aid of its counterpart and enabled the defeat and partition of the Principality of Benevento, notably by employing Muslim mercenaries.

Realizing the weakness of the states of the Mezzogiorno, the Saracens began to settle on the coasts of Campania and pillage the cities of the region. Following the Sack of Rome in 846, the Tyrrhenian Duchies organized themselves into a Campanian League to combat Saracen piracy, which was now regularly devastating the Italian coasts since their conquest of Sicily in 827, even establishing permanent bases in Apulia, such as Agropoli or Traetto^[18]. After defeating a Saracen fleet the same year at Licosia, they won an important victory in 849 during the Battle of Ostia, saving Rome from a second sack under the command of Caesar of Naples. The Saracen threat was ultimately definitively removed after the Battle of Garigliano, during which all the Christian powers of the Mezzogiorno allied to expel the Saracens from continental Italy.

The early 10th century saw regular conflicts between the Lombard princes and the Tyrrhenian dukes, who did not necessarily form homogeneous blocs. For example, in 946, Amalfi supported Salerno when it was attacked by Naples and Benevento^[19]. These internal struggles allowed the Byzantine Empire to return in force to the region during periods of strong territorial expansion driven by the Macedonian dynasty. It once again subjugated all of Apulia through the theme of Longobardia as well as part of Lucania, forming with Calabria the Catepanate of Italy. Both the Tyrrhenian dukes and the Lombard princes were forced to recognize themselves as vassals of the catepan while retaining very broad autonomy. They frequently oscillated between forced submission and open rebellion depending on the circumstances^[20]. Italy, however, remained a secondary theater for the Byzantines, especially when confronted with the arrival of the Seljuks in the 11th century, and the Tyrrhenian Duchies were often left alone in their struggle against the Lombards. This allowed the german emperors, and especially Lothair III to reassert its authority over Gaeta, Capua and Naples.

It was in this context that the first Norman adventurers arrived in southern Italy. Initially simple mercenaries in the service of the Lombard princes in their struggle against the Byzantines, it was Duke Sergius IV of Naples who first granted them a fief in 1029 by entrusting the County of Aversa to Rainulf Drengot^[21]. This concession aimed to protect Naples from the ambitious Lombard princes Pandulf IV of Capua and Guaimar IV of Salerno, who represented the last golden age of their states. The former occupied Naples between 1027 and 1030, allowing the definitive emancipation of the already highly autonomous Duchy of Sorrento^[15], and annexed Gaeta and Amalfi in 1032 and 1034, respectively^[16]. The latter inherited the titles of the former and annexed Sorrento in 1040, isolating Naples. However, Guaimar IV was assassinated in Amalfi in 1052 during a traditional internal feud, putting a definitive end to Lombard power.

Seizing the weakness of the main local potentates, whether Byzantine or Lombard, the Normans abandoned their mercenary status to undertake the conquest of southern Italy for their own account. They then took control of the entire Mezzogiorno in less than a century, completing their work with the creation of the Kingdom of Sicily in 1130. The Duchy of Naples was the last principality to fall into the hands of the House of Hauteville, as the last duke, Sergius VII of Naples, submitted in the same year, before seeing his duchy annexed in 1137. Naples, however, long retained a strong particularism in its legal acts, using specific formulas inherited from late antiquity that were incomprehensible to other notaries of the kingdom. It dated its acts not by the years of the king's reign but by the years of its "dominion" over the city. This particularism lasted throughout the Norman period and was only ended by Frederick II in 1220^[22].

• Éric Thoreau-Girault, Une société chrétienne : Naples, Amalfi, Gaète (vie-xiie siècle), Leuven/Paris/Bristol, Peeters, 2022.
• Jean-Marie Martin, Italies Normandes XIe - XIIe siècles, Paris, Hachette Litterature, 1994.
• Jean-Marie Martin (2017). "Les contrats agraires dans les duchés tyrrhéniens". L’héritage byzantin en Italie (VIIIe-XIIe siècle). Rome: Publications de l’École française de Rome. p. 319 à 340. ISBN 978-2-7283-1225-2..
• Jean-Marie Martin (2012). "Les aristocraties des duchés tyrrhéniens (Xe-XIIe siècle) : parcours variés de Byzance à l'Occident". L’héritage byzantin en Italie (VIIIe-XIIe siècle). Rome: Publications de l’École française de Rome. p. 585 à 604..
• Ferdinand Chalandon (1901). L'état politique de l'Italie méridionale à l'arrivée des Normands. Vol. 21. Mélanges de l'École française de Rome.
• Barbara M. Kreutz (1991). Before the Normans: Southern Italy in the Ninth and Tenth Centuries. Philadelphie: University of Pennsylvania Press.
• Jean-Charles-Léonard Simonde Sismondi (1840). Histoire des républiques italiennes du moyen âge. Treuttel et Würtz.