Drop Redoubt was a key component of the defences on the Western Heights of Dover. The Redoubt had the North Lines Battery immediately to its’ West and a short stretch of the Northeast Line running to the East. Initial construction was between 1804 and 1816, although some preparatory was done thirty years earlier. The Redoubt that stand now was primarily built between 1858 and 1867 which saw the building of a dry moat, caponiers and flanking galleries.
Drop Redoubt was primarily used as a saluting battery and barracks up until about 1850 when it was armed with a mixture of smoothbore weapons including three 24-pdrs on traversing platforms, six 12-pdrs in barbette emplacements (saluting battery) and a single 8-inch Mortar. For the next decade recommendations were made completing the work but it was not until April 1869 that eleven 7-RBL guns were mounted on the terreplein. At this time (1866) the caponiers were also modified to be double storey structures.
By 1886 the eleven 7-inch RBL guns remained mounted on the terreplein, with fifteen carronades now mounted in the caponiers and gun rooms covering the dry moat. Plans were drawn up to replace nine of the 7-inch RBL gun with six 64-pdr RBL guns (not mounted until 1892). The two retained 7-inch RBLs were intended to be covering the flank emplacements. Four of these six 64-pdr RML guns were placed in the new North Lines Battery. The 12-pdr carronades where to be replaced by 24-pdr Carronades and this was done by 1892. There were also two Machine Guns (Maxim) mounted on the walls by 1892.
In 1893 six 64-pdr RML guns were mounted on the North Lines running from the Drop Redoubt to the North Entrance, names as North Lines Battery.
By 1902 all the heavy guns had been removed with only the Maxim Machine Guns retained.