Half Moon Battery is on the southern edge of the Pendennis Peninsular, covering the entrance to Falmouth Harbour and Carrick Roads. The Battery originates from 1795 and by the 1860s was armed with four 64-pdr RML guns. Plans show the battery with two side arms sheds and a magazine traverse in 1880.
In 1894 the whole battery was modified to mount two 6-inch BL guns on HP mounts in pits.
In 1901 a Defence Electric Light was built on Pendennis Point to support the battery, with another light following in 1902.
Between 1909 and 1912 Half Moon Battery was completely remodelled. The new Half Moon Battery mounted two 6-inch Mark VII BL guns on Mark 2 mounts. This battery was accessed through a rock cut tunnel. The gun pits lay adjacent to each other with an underground shell store and magazine between them. There was a War Shelter in the gorge of the battery.