Cramond Island was one of the locations making up the Middle Defence Line of the Firth of Forth. The first guns appear to have been mounted on the Island in 1914, two 12-pdr QF guns. They were supported by Defence Electric Lights. A total of at lease six Defence Electric Lights were built on the Island.
During World War 2, these 12-pdr guns to have been replace by a Twin 6-pdr gun. A new 12-pdr gun emplacement was built covering the boom defences from the Southern tip of the Island to the Mainland.