Slough Fort is a small artillery fort that was built at Allhallows-on-Sea in the north of the Hoo Peninsula in Kent. Constructed in 1867, the D-shaped fort was intended to guard a vulnerable stretch of the River Thames against possible enemy landings during a period of tension with France. Its seven casemates initially accommodated rifled breech loading guns, which were replaced by the turn of the century by more powerful breech-loaders on disappearing carriages, mounted in concrete wing batteries on either side of the fort. It was likely one of the smallest of the forts constructed as a result of the 1860s invasion scare. All of the guns were removed by 1912, though the fort continued in use during the First World War as a command post. It was decommissioned in 1920 and sold off in 1929. Since the 1960s, it has been used as a stables adjoining a holiday camp. The camp's owners funded a partial restoration in 2012–13 that uncovered previously buried features of the fort. Strategic context The fort was constructed in response to a naval arms race between Britain and France. Britain's coastal defences had not been substantially upgraded since the Napoleonic Wars, but a new generation of accurate and powerful guns, mounted on fast-moving, manoueuvrable iron-clad warships, had rendered obsolete the existing 18th and early 19th century forts along the British coastline. The Thames was seen as particularly vulnerable; as well as being one of the country's most important trade routes, it possessed several naval installations of great importance, including the victualling yards at Deptford, the armaments works of Woolwich Arsenal, the shipbuilding yards at North Woolwich, and the magazines at Purfleet. The government's response to the increased threat was to appoint a Royal Commission on the Defence of the United Kingdom, which published a far-reaching report in 1860. It recommended that many existing forts should be upgraded or rebuilt entirely, and that new forts should be constructed to guard particularly strategic or vulnerable points along the coast. In all, around 70 forts and batteries were constructed around the English coast as a result of the Royal Commission's report. Slough Fort was probably one of the smallest of these. Construction The position of Slough Fort (which took its name from the now-disappeared farmsteads of Upper and Lower Slough, just west of the fort) was dictated by its position on a ridge overlooking a slope leading