The Firth of Forth assumed growing importance from March 1903 when work commenced on the new Rosyth Dockyard. Work on the dockyard did not start for six years and it was just being completed by 1914.
Designated as an A Class A Harbour by the Home Ports Defence Committee, later the Home Defence Committee with defences designed to withstand attack from Battleships.
By the end of the 19th Century there were six coastal defence batteries guarding the Firth of Forth. These were: