The earliest of the three levels of wartime tunnels is Casemate Level, which was constructed during the Napoleonic Wars. At this time the militia was permanently in occupation at the Castle; the construction of the casemates was instigated by the requirement for barracks. The use of such underground space was a revolutionary initiative at this time. The primary phase of construction includes the four smaller casemates to the west with upper floors, and three larger casemates to the east. North and south communication tunnels were also constructed, in addition to a small system of tunnels between the two groups of casemates and an access tunnel to the south which remains in use today. The casemates were brick lined by 1810 due to chalk falls. It was during World War II that Casemate Level played its most notable contribution in military history. From 1939 it was in use as a ‘Fortress Headquarters’ by the Army and Navy, controlling Naval vessels in the Straits of Dover
and deploying coastal artillery as well as anti-aircraft operations. Structurally the casemates were not altered at this time but were subdivided into smaller rooms to accommodate their new function. (summarised from sources) (1-2)

<1> English Heritage, 2014, Dover Castle Conservation Management Plan Volume 2 Gazetteer (Unpublished document). SKE52105.

<2> Johnathan Coad, 1995, English Heritage Book of Dover Castle and the Defences of Dover (Monograph). SKE52106.