The age of Guaimario III and his son, Guaimario IV, was the most important moment for the economic and political development of the Salerno lombardic principality. In fact, in that age, the principality reached the greatest territorial expansion and restored the glorious deeds of the Benevento’s principality at the age of Arechi II. At the same time, the princes of Salerno established very important diplomatic relationships with the papacy and teutonic emperors. An age of magnificence that, however, lasted less than a century, in consequence of the Norman Conquest. 

While the city was governed by Prince Guaimario III (989-1027), 40 Norman Knights arrived in Salerno, with one or more ships landed on the beach of La Carnale to the east of the city. La Carnale which could be used as a refuge and lookout point to follow the movements of the Saracens that besieged Salerno (999-1016).

As Leone Ostiense report in his "Chronica Monasterii Casinensis", that 40 cavaliers, who were "pilgrim warriors", came to visit the Holy Sepulcher in Jerusalem, where they had worshiped Jesus Christ.; men who were truly tall, handsome in appearance and exceptionally skilled in arms. Returning from the pilgrimage, most likely on an Amalfi ship: in fact at that time the Amalfi people often transported pilgrims to Jerusalem, who disembarked in Jaffa, and then took them back on their return from Egypt and Crete, where they had gone on business.

The Norman Knights eager to expel the Saracens from the city, managed to obtain weapons and horses from Guaimario, but, having to move on a territory they did not know enough, also obtained as a guide a Lombard "Knight from Salerno". The Crusaders hit the Saracens so hard and killed so many that the area where the battle raged took the name of "Carnale" and gave the same name to the homonymous fort built in the area centuries later. The miraculous victory that followed the battle, led by the "Knight from Salerno", to get the better of the Saracens, and thus free the city from the siege. 

Claiming to have done this only for the love of God and the Christian religion, the 40 Normans refuse any gift and say they cannot stay there. Therefore the prince, after consulting with his own, together with these same Normans, sends his own ambassadors to Normandy and sends there some fruit, citrus fruits, almonds, golden walnuts, purple robes, horse harnesses decorated with the finest gold. So he not only invited but dragged them to pass into a land that produced such things.

The "Knight from Salerno" was then nicknamed "the Knight of the Forty", from which the birth of the surname "Quaranta", which is therefore a surname of Salerno origins. 

The great adventure of the Normans in Italy which will see them unite all of Southern including Sicily in a single state, therefore began precisely in Salerno, which in 1076 it will become the first capital of the 2 Sicilies, thanks to the Norman Roberto il Guiscardo d'Altavilla, Duke of Puglia Calabria Sicily.

The famous landing of the 40 Normanni in Salerno and the consequent battle against the Saracens for the liberation of the city, are represented by the French painter Eugène Roger in a wonderful painting entitled "Levée du siège de Salerne" is kept in the Palace of Versailles near Paris.