What right/legitimacy did Normans have to a kingdom in Southern Italy?

Question

In the eleventh century the Northmen conquered England and created a Norman state in Southern Italy.

Why did Normans travel so far afield and what right/legitimacy did they have to a kingdom in Southern Italy?

Yes, I know, it would be simple to answer to this question saying "because it served their geopolitical interest to have a bastion on the Mediterranean sea and because there was no one to tell them that they were not allowed to", but, alas, history is often more complex than it appears.

So, the questions underlying this topic are: Was it the pope that allowed the Normans to create a kingdom in Southern Italy? Perhaps could we interpret the Norman conquest as a fight against schismatics?

Answer 1

The Norman kingdom in South Italy was certainly not a papal project. On the contrary, the popes tried to oppose the growing Norman power, by diplomatic and military means. Matters came to a particular head in 1053 in the battle of Civitate where the Normans defeated the Pope's army and took him prisoner. But eventually, when the papacy realized the Normans were there to stay, they reached an accord with it.

So far I've been just saying "The Normans" but in fact there was no central Norman organization at this stage (unlike in the Norman conquest of England which was led by the William the Duke of Normandy and was a centralized enterprise). What happened is that many young scions of Norman nobility, armed with little more than a sword and ambition (remember, under feudalism, the eldest son got the family estate, the other sons had to provide for themselves) made their way to South italy, a rich land whose petty Lombard princes were engaged in constant internecine warfare (and also against the Byzantines and the Arabs) and had a growing demand for good mercenaries.

So the Normans hired themselves out to the Lombard princes. With time, as more and more Normans settled in Italy, they naturally began to coalesce into warbands of their own and eventually obtained political power for themselves (much like the Turkish/Kurdish warriors in the service of Arab rulers during the khalifate's waning). As I have described above, during the process of obtaining political power they clashed with the other powers that be, including the papacy, and beat them.

(CORRECTED) Trivia point: the first Norman warrior to attain title and lands was one Ranulf Drengot.

A good source for this is The Normans in Sicily: The Normans in the South 1016-1130 and the Kingdom in the Sun 1130-1194 by John Julius Norwich.

Answer 2

I have found this passage in Runciman's A History of the Crusades:

In 1040 six brothers [...] took control of the city of Melfi [...]. [...] Henry III supported them in order to gain control on the region that he contended with the Eastern Empire. The German Pope, that he had elected, did the same, as he was scorned that the Eastern Patriarch had jurisdiction on an Italian diocese. In little more than twelve years, the sons of Tancredi had imposed their control on the Lombard principalities and had pushed the Byzantine towards the edges of Calabria and the shores of Puglia, they were threatening the Westerly cities* and in their raids they pushed North, through Campania in the neighbourhood of Rome. The Byzantine government was alarmed [...] but the Normans easily dispatched its small army, but had more success with diplomacy as the new Pope [...] Leo IX, was nervous. The Normans had achieved more than he and Henry III had expected.

• From the context these are Naples, Amalfi and Gaeta. The translation is mine as I have the Italian translation of the book.

I think that, from this passage, we can evince that the Normans indeed had some degree of legitimacy. What happened later, in that the Pope confronted the Normans, is indeed correct. However it refers to a later development, and also (likely) to a different Pope.

This is confirmed by another snippet that comes from Wikipedia's page about Drogo of Hauteville (unfortunately I do not have access to any of the texts referenced in the article).

On 3 February 1047, while the Emperor Henry III, was visiting southern Italy, he received Drogo's homage and invested him with all the territory which he already controlled. After this Drogo began using the title "Duke and Master of all Italy and Count of all the Normans of Apulia and Calabria".

(emphasis added). I would dare and say that the Normans' conquest of Southern Italy was mainly a consequence of an Imperial project, while papal support only came insofar as the Pope was (in that particular timeframe) a puppet of Henry III. The Holy Roman Emperor wished to re-establish his control on the whole Italian Peninsula, as he considered himself the successor of the Western Roman Emperors. This involved defeating the Byzantine as well as the Lombards (who settled the Appeninnes) and the Saracens (who occupied Sicily). He likely hoped to use the Normans as pawns, but when the latter consolidated their control on the whole region, he realized that the situation had gone out of his control. The new political entity was much stronger than the sum of its parts. So much so, that all previous Christian contenders in the region, the Byzantine, the Pope, the Lombards and Henry III joined their forces against the Normans.

This awkward coalition was however defeated in the Battle of Civitate, after which the future Kingdom of Sicily became one of the major powers in Europe, holding important roles in the Crusades, in the struggle between the Pope and the Holy Roman Emperor, and even attempting to conquer the Byzantine Empire.