Fortifications of Guernsey (fortified for several thousand years) had more than five places built, one of which was Castle Cornet.
The island of Guernsey has been fortified for several thousand years, the number of defence locations and complexity of the defence increasing with time, manpower and the improvements in weapons and tactics. Castle Cornet   Town Walls Gand tower Beauregard tower Pezeries   Jerbourg headland  Hommet headland  Fort Hommet  Le Marchant headland  Fort L'Angle   Inland fortress pre 600 A.D. Vale Castle   Chateau des Marais   
The island of Guernsey has been fortified for several thousand years, the number of defence locations and complexity of the defence increasing with time, manpower and the improvements in weapons and tactics. The Jerbourg Point defences resembled an Iron Age fort, it comprises a series of ditches and banks across the neck of the headland, providing a short defensive wall behind which the people could retreat in times of danger. Dating from 2,000 B.C. the Jerbourg defence of three ditches was improved, firstly with stone reinforcing and later with wooden platforms, palisades and a tower, however it fell to French invaders in 1338. The headland at Jerbourg, the Castel fortress, the Chateau des Marais and the Vale Castle were probably the earliest. Chateau des Marais, also called locally "Ivy Castle" built in a swamp, a "marais", using the natural wetland, supplemented with banks and ditches for defence built in the 12th century. as a standard Motte and Bailey fort. The castle of Saint Michael or as it is now called "Vale Castle", dating from the Iron Age, was constructed to protect the population against pirates by providing a safe refuge. It is not possible to identify when the medieval works were started, possibly in the late 10th-century. Castle Cornet was started in the late 13th Century on an islet accessible at low tide, outside Saint Peter Port. Work started in 1782 on the massive Fort George, on the hill south of Town, it would take over three decades to complete. It would serve as the main base for the Governor of Guernsey, the commander of the Island's military forces, for many centuries. 
