The Norman conquest of southern Italy spanned the late eleventh and much of the twelfth centuries, involving many battles and many independent players conquering territories of their own. Only later were these united as the Kingdom of Sicily, which included not only the island of Sicily, but also the entire southern third of the Italian Peninsula (save Benevento, which they did briefly hold on two occasions) as well as the archipelago of Malta and parts of North Africa.

Immigrant Norman brigands acclimatised themselves to the Mezzogiorno as mercenaries in the service of various Lombard and Byzantine factions, communicating news swiftly back home about the opportunities that lay in the Mediterranean. These aggressive groups aggregated in various places, eventually establishing fiefdoms and states of their own; they succeeded in unifying themselves and raising their status to one of de facto independence within fifty years of their arrival.

Unlike the Norman conquest of England (1066), which took place over the course of a few years after one decisive battle, the conquest of Southern Italy was the product of decades and many battles, few decisive. Many territories were conquered independently, and only later were all unified into one state. Compared to the conquest of England, it was unplanned and unorganised, but just as permanent.

Southern Italy or Il Mezzogiorno (Italian pronunciation: [meddzoˈdʒɔːrno], meaning 'Midday') is the traditional term for the southern half of the Italian state, encompassing the southern section of the continental Italian Peninsula and the two major islands of Sicily and Sardinia. It coincides with the administrative regions of Basilicata, Campania, Calabria, Apulia, Molise, Sicily, and finally Sardinia, that is considered as part of Southern Italy more for economic reasons than for cultural, historical or geographical reasons. Some also include Abruzzo and the most southern and eastern parts of Lazio (Sora, Cassino, Gaeta, Cittaducale and Amatrice districts) within the Mezzogiorno, because these territories were part, along with all the already listed ones (except Sardinia), of the historical Kingdom of Two Sicilies.

Southern Italy carries a unique legacy of peculiar nature, archeology and culture. It features many major tourist attractions, such as the Palace of Caserta, the Amalfi Coast, Pompeii, Herculaneum, and other archaeological sites (many of which are protected by UNESCO). Some of its beaches, woodlands and mountains are preserved in several National Parks. Some medieval towns are located in Southern Italy. The history of Southern Italy boasts numerous kings, queens, princes, popes, writers, poets, philosophers, knights, artists, architects, craftsmen, musicians, scholars, scientists, politicians and farmers.

Italy ⁱ/ˈɪtəli/ (Italian: Italia [iˈtaːlja]), officially the Italian Republic or the Republic of Italy (Italian: Repubblica italiana), is a unitary parliamentary republic in south-central Europe. To the north, it borders France, Switzerland, Austria and Slovenia along the Alps. To the south, it consists of the entirety of the Italian Peninsula, Sicily, Sardinia–the two largest islands in the Mediterranean Sea–and many other smaller islands. The independent states of San Marino and the Vatican City are enclaves within Italy, while Campione d'Italia is an Italian exclave in Switzerland. The territory of Italy covers some 301,338 km² (116,347 sq mi) and is influenced by a temperate seasonal climate. With 60.6 million inhabitants, it is the fifth most populous country in Europe, and the 23rd most populous in the world.

Rome, the capital of Italy, was for centuries a political and religious centre of Western civilisation as the capital of the Roman Empire and site of the Holy See. After the decline of the Roman Empire, Italy endured numerous invasions by foreign peoples, from Germanic tribes such as the Lombards and Ostrogoths, to the Byzantines and later, the Normans, among others. Centuries later, Italy became the birthplace of Maritime republics and the Renaissance, an immensely fruitful intellectual movement that would prove to be integral in shaping the subsequent course of European thought.

The Norman conquest of England was the invasion and conquest of England by an army of Normans and French led by Duke William II of Normandy. William, who defeated King Harold II of England on 14 October 1066 at the Battle of Hastings, was crowned as king on Christmas Day 1066. He then consolidated his control over England and settled many of his followers in England, introducing a number of governmental and societal changes to medieval England.

William's claim to the English throne derived from his familial relationship with the childless King Edward the Confessor, who may have encouraged William's hopes for the throne. But when Edward died in January 1066, he was succeeded by his brother-in-law Harold, who not only faced challenges from William but also another claim by the Norwegian king, Harald Hardrada. Hardrada invaded northern England in September 1066, winning a victory at the Battle of Fulford before being defeated and killed by King Harold at the Battle of Stamford Bridge on 25 September 1066. William, however, had landed in southern England, and Harold quickly marched south to confront William, leaving many of his forces behind in the north. On 14 October Harold's army confronted William's invaders near Hastings and after an all day battle, was defeated and killed.