Jersey – the largest of the Channel Islands – has been an island for around 6,000 years. Early inhabitation is evidenced by various neolithic monuments and hoards. In the 10th century, Jersey became part of Normandy. When the Normans conquered England in the 11th century, Jersey remained a part of the Duchy of Normandy, but when Normandy and England were finally split in the 13th century, the Channel Islands remained loyal to the English Crown, splitting Jersey politically from mainland Normandy.

Due to the English kings' continuing claim to the Duchy of Normandy, Jersey's Norman political and legal structures remained after the split, which led to the establishment of self-governance as a Crown Dependency. Between the 11th and 15th centuries, political tensions between England and France placed Jersey at the frontline of frequent wars.

During the Tudor period, the English Crown split from the Roman Church and immigration to the island of French religious refugees led to the establishment of Calvinism as the major religion of the island. In 1617, the Privy Council separated the powers of Governor and Bailiff, establishing that the Bailiff had sole jurisdiction over justice and civil affairs in the island. During the English Civil War, Jersey remained more loyal to the Crown due to the loyalties of the de Carteret family, though the island was eventually captured by Parliamentarian forces. After restoration, the de Carterets were gifted land in the American colonies, establishing New Jersey.

In the 18th century, Jersey experienced bouts of unrest, culminating in the Corn Riots of 1769. As a result, legislative power was concentrated in the States in 1771, stripping the Royal Court of its lawmaking abilities. Island politics was then split between the Magot and Charlot parties through much of the 19th century. In 1781, the island was invaded by the French, but was defeated by an army led by Major Francis Peirson in the Battle of Jersey. From 1815, new peace with the French meant the island lost strategic military value. Improvements in transport infrastructure led to non-political increased links with the United Kingdom. Alongside this, a rising sense of British nationalism led the island's culture, which had previously retained many Norman-French qualities, to become highly anglicised.

The islands were away from the frontline of the First World War, but during the Second World War, the Channel Islands were the only part of the British Isles to be occupied by enemy forces. From 1940 to 1945, Jersey was occupied by German forces. The islands were liberated on 9 May 1945, which is still celebrated as the island's national day. After liberation, the island became a popular tourist destination and has become a major offshore finance centre.

Name of the island Although Jersey was part of the Roman world, there is a lack of evidence to give a better understanding of the island during the Gallo-Roman and early Middle Ages. The tradition is that the island was called Caesarea by the Romans as laid down in the Antonine Itinerary, however this is disputed by some, who claim Caesarea, Sarnia and Riduna are the Scilly Isles off the southwestern tip of England, nevertheless Sarnia in particular has a large cultural influence as the historic name of Guernsey (for example the national anthem of Guernsey is Sarnia chérie). Andium however is also mentioned on the list and this name is very often attributed to Jersey. Therefore, it is possible another island, such as the Minquiers were in fact Caesarea and Jersey Andium.

The name is claimed to be the source of the modern name Jersey, -ey being a Norse signification of an island, and Jer- possibly being a contraction of Caesar, similar to Cherbourg, therefore the island meaning Caesar's island. Another claim for the origin of the name is as Geirr's Island from the Norse name Geirr or as the grassy isle from the Frisian gers.:16 The Roman name for the Channel Islands was I. Lenuri (Lenur Islands)

Some claim that the pre-Roman name for the island was Augia (alternatively Andium), and it was given by this name by King Childebert of France to Archbishop Samson of Dol in 550 CE. In the past the island's name has various variations of its spelling, such as Gersey, Jarzé, Gerzai and Gersui (including re-latinisations such as Gersoium and Grisogium) Andium has considerable popularity as the former name for Jersey, being for example the name of the island's social housing corporation.

Origins of other place names on the island L'Etacq is of Norse origin, a derivative of L'Estack, from the Norse stakkr, meaning high rock. This word also gives name to various places called Etacquerel.:16

Prehistory

The earliest evidence of human activity in Jersey dates to about 250,000 years ago in the Middle Paleolithic (before Jersey became an island) when bands of Neanderthal nomadic hunters used the caves at La Cotte de St Brelade as a base for hunting mammoth and woolly rhinoceros. The inland Les Varines site indicates that Jersey was occupied by modern humans of the late Upper Palaeolithic Magdalenian culture towards the end of the last ice age.

Due to rising sea levels, Jersey has been an island for approximately 6,000 years. The geology of the Channel Islands, has its origins in the Hercynian mountain building period, which also accounts for the hills of Brittany and the moors of Devon and Cornwall. At its current extremes it measures east to west and north to south. Evidence of Ice Age period engravings dating from at least 12,000 BC has been found, showing occupation by Homo sapiens.

Evidence also exists of settled communities in the Neolithic period, which is marked by the building of the ritual burial sites known as dolmens. The number, size, and visible locations of these megalithic monuments (especially La Hougue Bie) have suggested that social organisation over a wide area, including surrounding coasts, was required for the construction. Archaeological evidence also shows that trading links with Brittany and the south coast of England existed during this time.

Hoards

Evidence of occupation and wealth has been discovered in the form of hoards. In 1889, during construction of a house in Saint Helier, a 746-gram gold torc of Irish origin was unearthed. A Bronze Age hoard consisting of 110 implements, mostly spears and swords, was discovered in Saint Lawrence in 1976 – probably a smith's stock. Hoards of coins were discovered at La Marquanderie, in Saint Brelade, Le Câtel, in Trinity, and Le Câtillon, in Grouville (1957).Balleine's History of Jersey, Marguerite Syvret and Joan Stevens (1998)

In June 2012, two metal detectorists announced that they had uncovered what could be Europe's largest hoard of Iron Age Celtic coins, 70,000 late Iron Age and Roman coins. The hoard is thought to have belonged to a Curiosolitae tribe fleeing Julius Caesar's armies around 50 to 60 BC.

In October 2012, another metal detectorist reported an earlier Bronze Age find, the Trinity Hoard.

Early history

Prior to Normandy Although there is no evidence of a Roman occupation of Jersey, historians consider that it is entirely feasible it was occupied by the Romans. Various Roman archeological artefacts have been found on the island, such as coins discovered on the north coast at Ile Agois. There are several sites attributed to the Romans on the island, such as Caesar's fort at Mont Orgeuil. Roman influence has been found, in particular at , the coastal headland site at Le Pinacle, where remains of a primitive structure are attributed to Gallo-Roman temple worship (fanum).

When Augustus Caesar divided Gaul into four provinces, Jersey was part of the province headquartered at Lyons. Roman influence has a strong grounding in the development of Jersey culture, bringing vernacular Latin to the isle, which would later develop into Standard French and Jèrriais (and influence English).

During the migration of the Britons from Britain to Brittany (c. 5th – 6th century AD), specifically during the invasion led by St Samson, Bishop of Dol, it is believed the Channel Islands came to be settled by them. There are numerous references to the habitation of Jersey by Breton people. This likely brought Christianity to the island. Various saints such as the Celts Samson of Dol and Branwalator (Brelade) were active in the region. Tradition has it that Saint Helier from Tongeren in modern-day Belgium first brought Christianity to the island in the 6th century; part of the walls of the Fishermen's Chapel dates from this period and Charlemagne sent his emissary to the island (at that time called Angia, also spelt Agna) in 803. A chapel built around 911 now forms part of the nave of the Parish Church of St Clement.

Duchy of Normandy (873–1204) From 873, Jersey was affected by the conquests by the Normans of the western coast of France (the Channel Islands were territory of the Kingdom of France at this time). During the reign of Charles III the Simple, the territory of modern Normandy was yielded to Rollo, the leader of the Normans, with the title of the "Duke of Normandy". While the Duchy was held in fief to the French Crown, the Crown only had limited rights in the province.

In around 933, Duke William I (William Longsword), seized Jersey, which until then had been politically linked to Brittany, and it is likely that the pre-Norman form of government and way of life was replaced at this point. The island adopted the Norman law system, still the basis of Jersey law today. During Norman rule, the island redeveloped after the devastation brought by the Vikings and developed agriculture. Immigration from the Norman mainland at this time first brought the modern Norman cultural influences found in the island today.:19

A key part of the early administrative structure of Jersey was the fief. Alongside the parish, the fief provided a basic framework for rural life; the system began with the Norman system and largely remained similar to it. In Jersey, the dues, services and rents owed by tenants were extensive and often onerous. Jersey peasants retained a degree of freedom lost elsewhere, probably due to the insignificance of the island in the Duchy. More is known of the origins of the fief than of the parishes and early documents show that Jersey was thoroughly feudalised (the majority of the residents were tenants holding land from Seigneurs). The fief of St Ouen, the most senior fief in Jersey's feudal structure, was by 1135 in the hands of the de Carteret family. They held extensive lands in Carteret as well, but these were lost by them after King John's loss of Normandy, so they decided to settle on the island. Between the 12th and 20th centuries, there were an estimated 245 fiefs in Jersey, though not all simultaneously.

In 1066, the Duke William the Conqueror defeated Harold Godwinson at Hastings to become the King of England; however, he continued to rule his French possessions, including Jersey, as a separate entity, as fealty was owed to the King of France. This initial association of Jersey with England did not last long, as William split his possessions between his two elder sons: Robert Curthose became Duke of Normandy and William Rufus gained the English Crown. After William Rufus' death his younger brother Henry I claimed the English throne, and recaptured Normandy for England in 1106. The island was then part of the English King's realm (though still part of Normandy and France). Around 1142, it is recorded that Jersey was under the control of the Count of Anjou, who administered Normandy for the Duke.