Taken from source:

Fort Burgoyne was completed in 1868, yet it would seem that this 19th century work, representing one of the last permanent land forts to be built in Britain, was not constructed on a completely new site. Flinders Petrie in his notes on Kentish Earthworks published in Archaeologia Cantiana in 1880 states that '… at Dover, the camp NW of the Castle has been destroyed by a modern fort'. He cites no particular authority for the existence of this earlier work and little other information is readily available. Nevertheless, a map of the NE Castle defences drawn in 1756 and published by Coad and Lewis in 1982 incidentally shows a circular earthwork some 60m in diameter adjoining the east side of the road at Guston village, 580m to the north of the Castle keep. This is marked as 'Olivers Mount' and plotting it on a modern map places it immediately to the south of Fort Burgoyne in an area long occupied by Connaught Barracks. All traces of the earthworks have now gone but the presence of this structure on a mid 18th century map clearly indicates that it was then a significant feature within the landscape. The exact purpose of these earthworks is unknown and a date cannot be ascertained beyond the assumption that it predates the 18th century. Perhaps the most likely interpretation is that it relates to the field works thrown up by the French during the seige of 1216 and could perhaps represent a temporary earth castle in the form of a motte or ring work. (1)

<1> Keith Parfitt, 1995, Kent Archaeological Review: A Lost Earthwork Near Dover Castle Vol. 121, KAR 121 pp. 10-11 1995 (K. Parfitt) (Article in serial). SKE31870.