The Lombard Principality of Salerno was a medieval Southern Italian state, formed in 851 AD out of the Principality of Benevento after a decade-long civil war. It was centred on the port city of Salerno. The Principality consisted of Taranto, Cassano, Cosenza, Paestum, Conza, Potenza, Sarno, Cimitile (Nola), Capua, Teano, and Sora. It was a maritime power with numerous seaports, including Salerno itself, and controlled mostly the western half of the old duch

Although it owed allegiance at its foundation to the Carolingian emperor, it was de facto independent throughout its history and alternated its allegiance between the Carolingians and their successors in the West and the Byzantine emperors in the east. In the first half of the 1000 AD it included almost all of southern continental Italy. 

"Opulenta Salernum" was the diction minted on the coins that were struck by the city for its trade in the 10th and 11th centuries, to testify the moment of particular splendor.

In 839 AD, the prince of Benevento, Sicard, died. Immediately, his chief army officer, Radelchis, seized power in Benevento and imprisoned Sicard's heir and brother, Siconulf, in Taranto. Amalfitan merchants rescued Siconulf from prison, and he was proclaimed prince in Salerno. A civil war erupted in the Italian Mezzogiorno. In 847, Emperor Lothair I had Guy I of Spoleto and Sergius I of Naples mediate a division of the great Lombard principality. In 849, Louis, King of Italy, the Radelgisi et Siginulfi principum Divisio Ducatus Beneventani, divided the principality into two sections: one with its capital at Salerno and another with the original Benevento.

The principality did not enjoy stability in its early years. In 851, Siconulf died and his son Sico was still a child. He was deposed and replaced by his regent, Peter, in 853, and Peter was succeeded that year by his son Adhemar. Adhemar's stormy princeship ended violently: a revolt deposed him, and Guaifer, the scion of a local family of note, the Dauferidi, had him blinded and imprisoned. Guaifer succeeded him in the princely office with the support of the people.

Guaifer stabilised the principality during his long reign of nineteen years. His successors reigned for similarly lengthy periods, and in a short time Salerno surpassed Benevento in greatness. During his reign, Capua made itself independent. Salerno was still technically a vassal of the Western emperor, but it was practically independent. The prince even allied himself with the Saracens.

In 880, Guaifer was removed in a precedent-setting act by his son: Guaimar I forced him into a monastery and took up the reins of government. The chronicles of his reign describe him in despotic terms, and he does not seem to have been popular. He did reverse the alliance with the Saracens in favour of closer ties to the emperor, then Charles the Bald. In 887, however, he broke with the West and paid homage to the Byzantine Emperor, receiving the title of patricius. In 900 or 901, his son, Guaimar II, forced him into his own monastic foundation of San Massimo and began his reign.

Guaimar II raised Salerno to greatness. He was a more religious prince than his father, who had been pious by the standards of the time. He introduced the Cluniac reforms to Salerno. He was also more inclined to war with the Muslims and took part in the famous Battle of the Garigliano in 915. In this he was the ally of the Byzantines, as he was throughout his reign, with the exception of a brief period in the 920s. He increased his prestige and influence through marriage alliances with the Beneventans and Capuans, and even entered into successful schemes against the Byzantine Campania, where he gained much ground. Guaimar further worked to stabilise his dynasty by altering the pattern of succession. He appointed his son Gisulf I as co-prince in 943, and Gisulf succeeded in 946.

The succession was not uncontested from without. The allied forces of John III of Naples and Landulf II of Benevento invaded, but an alliance with the Amalfitans saved Gisulf's reign. Gisulf like his father remained with the Greeks, even warring with the pope. He concluded a treaty with the latter and came to the defence of Pandulf Ironhead, the prince of Benevento and Capua. Though his neighbours constantly seemed to be opposing him, the Ironhead reinstalled him after an insurrection of 974, which had been supported by his brother and the neighbouring Greek cities. Gisulf did not have any children at his death, and Salerno passed into the wider realm of the Ironhead, who bestowed it on his son Pandulf II.

From 978, the year of Prince Gisulf's death, to 983, when the Salernitans reinstated a dynasty of their choosing, the principality was under the rule of "foreigners": either of the Capuan princely house or the dukes of Amalfi. The Amalfitans took advantage of the Ironhead's death in 981 to seize it from Pandulf II, and Manso I of Amalfi was made prince. He was unpopular, and a Spoletan, John, son of Lambert, was elected after the expulsion of the Amalfitans. Discordant relations prevailed with Amalfi until the end of the principality a century later.

John established his own dynasty, which was to usher in Salerno's final period of greatness as an independent Lombard entity. He tried to increase control of the church in his region, but failed. He followed the principle of co-regency of sons, to stabilise the succession. His son, Guaimar III, had to deal with Saracen attacks, but was aided by the Norman mercenaries he had helped to recruit to the south. He moved away from Byzantium throughout his reign and supported the Lombard rebels of Melus of Bari. He also supported his neighbour, Pandulf IV of Capua, despite the latter's unpopularity. Under Guaimar III, the Schola Medica Salernitana first began to flourish, and he was capable of striking "Opulenta Salernitanum" on his coins as a sign of the trading wealth of his city.

Guaimar IV brought Salerno to its greatest heights, but it did not survive him. He, too, used the Normans for mutual gain. He can be considered chiefly responsible for the rise of the Hautevilles in the Mezzogiorno. He opposed Pandulf of Capua, unlike his father, and he united his principality with that one for the first time since Pandulf Ironhead.

In 1038, he sought the arbitration of both emperors over matters concerning Pandulf, but only the Holy Roman Emperor, Conrad II, responded, and Salerno became fully Western in allegiance. Conrad made Guaimar a powerful prince, and he extended his authority militarily over the coastal city-states of Gaeta, Naples, and Amalfi. He opened up the Campania, Apulia, and Calabria to conquest and between 1038 and 1047 he was in control of all the continental southern Italy. But his successes were reversed by Conrad's son, Henry III, who in 1047 removed Guaimar from Capua and restructured the nature of his suzerain-vassal relationships to limit his power.

In 1052, Guaimar was assassinated, and his son and successor, Gisulf II, showed none of his political acumen. Under Gisulf, Salerno declined. He made useless war on Amalfi and on his Norman neighbours, finally on Robert Guiscard, the duke of Apulia, himself. Though Salerno remained wealthy and opulent to the end of his reign, he misused this wealth during the siege of 1077 and lost his city and his principality to the Guiscard.

With Gisulf's defeat, Salerno ceased to be the capital of a large principality, and its once vast domain was completely merged into the Duchy of Apulia and Calabria, the peninsular possession of the Hauteville family.

Salerno did continue as the most important city of southern Italy until the end of Hauteville rule in 1194, before being punished for its former rebellion against the Hohenstaufen dynasty in 1191, during which its populace handed over the entrusted Empress Constance to Tancredi, King of Sicily, leading to her effective captivity until May 1192. As a consequence, emperor Henry VI destroyed Salerno and since then the city never recovered its former importance, being substituted in southern continental Italy by Naples.

Princeps of Salerno

Siconidi (840 - 853)

840–851 Siconolfo

851–853 Sicone II

Not dynastic (853 - 861)

853 Pietro

853–861 Ademaro

Dauferidi (861 - 978)

861–880 Guaiferio

880–900 Guaimario I

900–946 Guaimario II

946–978 Gisulfo I

Landolfidi (978 - 981)

978–981 Pandolfo I Testaferrata, also Prince of Benevento (from 961) and Capua (from 961), and Duke of Spoleto (from 967)

981 Pandolfo II

Amalfi occupation (981 - 983)

981–983 Mansone, also Duke of Amalfi (966-1004)

981–983 Giovanni I, son and co-regent of Mansone

Dinastia di Spoleto (983 - 1052)

983–994 Giovanni II

994–1027 Guaimario III

1027–1052 Guaimario IV, also Duke of Amalfi (1039-1043) and of Gaeta (1040-1041), and Prince of Capua (1038-1047)

Landolfidi (1052)

1052 Pandolfo III

Dinastia di Spoleto (1052 - 1077)

1052–1077 Gisulfo II

The advent of the Normans and the end of the principality

In May 1076 Salerno was besieged by the troops commanded by Roberto il Guiscardo, brother-in-law of Gisulfo II, and by Riccardo di Aversa. The city capitulated after an exhausting resistance on 13 December 1076. Prince Gisulfo II surrendered to the invaders the following year and the Principality, the last Lombard stronghold in Italy, collapsed. Salerno and its domains were incorporated into the new Norman state and the city became the capital of the Duchy of Puglia and Calabria, ruled by the Guiscardo. To succeed him at the helm of the duchy was first his son and then his grandson. On the death of the latter without heirs, the fiefdom passed into the hands of Roger II, king of Sicily, who unified the whole territory of southern Italy.

1059-1085 Roberto il Guiscardo

1085-1111 Ruggero Borsa

1111-1127 Guglielmo d'Altavilla

1127-1130 Ruggero II, poi Re di Sicilia

Princes of the fief of Salerno

After the establishment of the Kingdom of Sicily in 1139, the Principality of Salerno was reconstituted as a fief under the crown. This feud for some periods was part of the state property of the kingdom at other times it was ruled by important aristocratic families. Whoever ruled the fiefdom was awarded the title of "Prince of Salerno".

1272-1285 Carlo II d'Angiò

1289-1295 Carlo Martello d'Angiò

1301- Tristano d'Angiò (ninth son of Carlo II d'Angiò)

1304-1309 Roberto d'Angiò

1334- Giovanna d'Angiò

1345-1348 Carlo Martello (son of Giovanna I)

1419- Giordano Colonna

-1433 Antonio Colonna

1439- Raimondo Orsini detto Raimondello

-1461 Felice Orsini

1463-1474 Roberto Sanseverino -  (c. 1430–1474): First Prince of Salerno, Grand Admiral of the Kingdom of Naples, and a notable patron of the arts

1463-1485 Antonello Sanseverino

1485-1500 Alfonso di Aragona

1500-1509 Roberto II Sanseverino

1553 Ferrante Sanseverino - (1507–1568): Fourth and last Prince of Salerno, condottiero, and Renaissance patron, famous for his opposition to the Spanish Inquisition

1572-1590 Nicola Grimaldi

The last to boast the title of Prince of Salerno was Leopoldo di Borbone from 1817 to 1851.