Apart from a Roman Fort, there were very few fortifications in Alderney until the mid 19th century. These were then modified and updated in the mid 20th Century by Germans during the occupation period. Alderney island is now one of the most fortified places in the world.
The Victorian era fortifications were built after 1845 against the naval threat from France. Completed in 1855, Fort Clonque, the most westerly in Alderney, connected by a causeway, mounting ten guns with a crew of 59 and bomb proof buildings. Originally the barracks were on the shore, making it impossible to get to the fort to man the guns at high tide.
Fort Tourgis was also completed in 1855. It was the second largest fort on the Island, mounting 33 guns in five batteries requiring 346 men. Sufficient accommodation was available in the fort. Built on a headland covering the bays of Clonque and Plattes Saline with many loopholed walls. Along the second beach, two batteries were built, Platte Saline and Doyle with three and four guns. Used by the Alderney militia until it was disbanded in 1882 and the militia artillery until 1929.
There are around ten more smaller forts as well built by British armies.
Arriving in an almost deserted island in 1940, all but 18 of the population having evacuated to England, the 450 Germans manned the existing fortifications until in 1941 when a decision was made by Adolf Hitler to fortify the Channel Islands. The majority of the work was given to the Organisation Todt. Workers were brought to the Island and installed in camps. The four camps by January 1942 held 6,000 workers.
Camp Sylt held Jews who were treated as slaves and camp Norderney held forced labour mainly Russian and Polish POW's but including men from many other nationalities were run by the OT until the SS took them over in March 1943. Those that survived the harsh treatment were shipped back to France to work on the Atlantic Wall when that became a higher priority. There are 397 known graves in Alderney and about 200 died when two German minesweepers were sunk by two Allied Destroyers on 7/8 July 1944.
References:Saint-Georges de Boscherville Abbey is a former Benedictine abbey. It was founded in about 1113 by Guillaume de Tancarville on the site of an earlier establishment of secular canons and settled by monks from the Abbey of Saint-Evroul. The abbey church made of Caumont stone was erected from 1113 to 1140. The Norman builders aimed to have very well-lit naves and they did this by means of tall, large windows, initially made possible by a wooden ceiling, which prevented uplift, although this was replaced by a Gothic vault in the 13th century. The chapter room was built after the abbey church and dates from the last quarter of the 12th century.
The arrival of the Maurist monks in 1659, after the disasters of the Wars of Religion, helped to get the abbey back on a firmer spiritual, architectural and economic footing. They erected a large monastic building one wing of which fitted tightly around the chapter house (which was otherwise left as it was).