Dover Harbour was designated as a Class A harbour the Home Ports Defence Committee, later the Home Defence Committee with diverse naval facilities. It was designed to resist attack from Battleships.
Between 1889 and 1901 new breech loading guns were mounted in Dover. The two new batteries were:
- Langdon Battery which lies to the east of Dover Castle. The battery was completed by 1901 and mounted three 9.2-inch Mark X guns and two 6-inch Mark VII guns.
- Citadel Battery, just to the west of the Citadel was completed by 1898 with three 9.2-inch Mark X guns, although one of these guns was withdrawn in 1910.