 It was initially a front-line fortification, supported by Shornemead Fort and Cliffe Fort located to the south and east respectively on the Kent shore.Over time, as batteries and forts further downriver became the front line of the Thames defences, Coalhouse Fort was stripped of its main weapons and it was altered to support smaller quick-firing guns intended to be used against fast-moving surface and aerial targets.Its last military use was as a training facility for a few years after the Second World War.