Garrison Point Fort is a former artillery fort situated at the end of the Garrison Point peninsula at Sheerness on the Isle of Sheppey in Kent. Built in the 1860s in response to concerns about a possible French invasion, it was the last in a series of artillery batteries that had existed on the site since the mid-16th century. The fort's position enabled it to guard the strategic point where the River Medway meets the Thames. It is a rare example of a two-tiered casemated fort – one of only two of that era in the country – with a design that is otherwise similar to that of several of the other forts along the lower Thames. It remained operational until 1956 and is now used by the Sheerness Docks as a port installation. 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 obsoleted 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. Garrison Point had long been fortified. A square blockhouse was constructed there by 1547, during the reign of Henry VIII. It was in the process of being replaced with a new fort when it was destroyed in the June 1667 Raid on the Medway during the Second Anglo-Dutch War. It was rebuilt as a bastion fort by 1669 to a design by Bernard de Gomme, who also designed Tilbury Fort further upriver. Two additional fortifications, the Half Moon Battery and Cavalier