The island of Guernsey and the other Channel Islands represent the last remnants of the medieval Duchy of Normandy.
During the Middle Ages, the island was a haven for pirates that would use the "lamping technique" to ground ships close to her waters.
The allegiance was not total, however; there were a few Royalist uprisings in the southwest of the island, while Castle Cornet was occupied by the Governor, Sir Peter Osborne, and Royalist troops.
In December 1651, with full honours of war, Castle Cornet surrendered - the last Royalist outpost anywhere in the British Isles to surrender.
The jurisdiction is made up of ten parishes on the island of Guernsey, three other inhabited islands (Herm, Jethou and Lihou), and many small islets and rocks.
The jurisdiction is not part of the United Kingdom, although defence and most foreign relations are handled by the British Government.
Anyone molesting Islanders would be excommunicated. The neutrality lasted another century, until William III of England abolished the privilege due to privateering activity against Dutch ships.
In the mid-16th century, the island was influenced by Calvinist reformers from Normandy.
Guernsey was very heavily fortified during World War II, out of all proportion to the island's strategic value.This article is about the eponymous island, the administrative unit, and the jurisdiction of Guernsey.For the whole Bailiwick, see Bailiwick of Guernsey. For other uses, see Guernsey (disambiguation).) is an island in the English Channel off the coast of Normandy.Wars against France and Spain during the 17th and 18th centuries gave Guernsey shipowners and sea captains the opportunity to exploit the island's proximity to mainland Europe by applying for letters of marque and turning their merchantmen into privateers.By the beginning of the 18th century, Guernsey's residents were starting to settle in North America, The early 19th century saw a dramatic increase in the prosperity of the island, due to its success in the global maritime trade, and the rise of the stone industry.
Le Braye du Valle was drained and reclaimed in 1806 by the British Government as a defence measure.