Summarised from report:

One of the major features of the Drop Redoubt Fort on Dovers western Heights is the deep pentagonal ditch which surrounds it. The ditch, which is linked on the east and west to the North-East Line and North Lines respectively, is cut from the chalk bedrock to a basal width of between 13.0 and 14.0m. The ditch is generally level, but earthen banks have been built up against the south-west, north-west, north-east and east walls (1.1m, 0.8m, 1.2m and 0.9m high respectively), though not along the south wall. The function of these banks was to absorb artillery fire aimed at the base of the wall (in order to make it collapse).The ground in front of each caponier was excavated to form a drop ditch, now only 0.8m deep but originally significantly deeper and fenced off to prevent enemy access to the loopholes of the caponier. Though work on the Drop Redoubt ditch was planned in the late 18th century, the main phase on construction was between 1803 and 1816, with most of the works on the ditch being completed by 1805. (1)

An early plan dating to 1811 shows the form of the ditch of The Drop Redoubt Fort after the completion of the Napoleonic works at the there. It is clear from this that the ditch remained the same (in plan) throughout the subsequent use of the fort. (2)

A later plan dating to 1860, shows the interior features of the Drop Redoubt Fort, alongside the layout of the Ditch, immediately before any alterations were made. (3)

<1> English Heritage, 2000, The Western Heights, Dover, Kent. Report No 3 The Drop Redoubt: A 19th-Century Artillery Fortification (Unpublished document). SKE13677.

<2> Major W H Ford, Royal Engineers, 1811, Plan Shewing the Appropriation of the Ordnance Lands on the Western Heights Dover 1811 (Map). SKE51523.

<3> Unknown, 1860, Drop Redoubt, Dover, Plan, Sections and Elevation Shewing Proposed Alterations And Additions (Map). SKE51528.