The three principal islands making up the Channel Islands are Jersey, Guernsey and Alderney. The proximity of the Islands to France made them vulnerable to attack from this direction, as shown by the German Occupation in World War 2.
By 1905 most of the old sites were redundant with the following coastal defences in place:
Fort Albert – Two 6-inch BL guns
Roselle Battery – Two 12-pdr Q.F. guns
In 1905 the coastal defences in Jersey were concentrated around St Helier with:
Elizabeth Castle – Two 4.7-inch Q.F. guns on the Cavalier
South Hill Battery – Two 12-pdr Q.F. guns, later upgraded to two 6-inch Q.F.
The coastal defence batteries were concentrated in Saint Peter’s Port. By 1905 we have:
Fort Irwin – Two 6-inch Q.F. guns
Cavalier Battery, Castle Cornet – Two 12-pdr Q.F. guns