History of River defence and the building of Cliffe Fort.
The Thames estuary is a wide and straight channel, with mudflats and shallow water along its sides, acting as a natural impediment to an enemy landing. Upstream at the Lower Hope, the river first begins to narrow and then bends into Gravesend Reach. This was a key place at which to deny the entry of enemy warships by the fire of heavy guns sited on the shore, especially if supported by the additional barrier of a river minefield. It was this strategic factor which, in the 1860s during a Cold War with France, led to the construction of Cliffe Fort on the riverbank, just south of Cliffe Creek.
This was an element of a nationwide upgrading of the coastal defences, which had been recommended in the findings of the Royal Commission on the Defence of the United Kingdom, presented in their report in 1860.As part of a networked system of defence, Cliffe Fort crossed its fire in a defensive triangle with Coalhouse Fort at East Tilbury opposite on the Essex shore and with Shornemead Fort on the Kentish shore 2.5 km upstream. This trio of forts was the outer line of defence to protect the river route to London, an inner line being based on a pair of forts upstream at Gravesend and Tilbury. The threat was them of attack by the new French steam ironclads, armed with powerful rifled muzzle-loading guns, firing shells of devastating destructive power.
The grey and brooding mass of the D-shaped fort is a prominent feature of the riverine landscape. The arc of its river-facing armoured casemates and open battery was armed with heavy rifled muzzle-loading guns of 9 in., 11-in. and 12.5-in. calibre to counter the threat of French ironclads, while defensible barracks closed the rear against the possibility of attack by a landing force. In the enclosed centre was a parade ground. Although not visible today, the river front of the fort was originally provided with a defensive ditch into which projected infantry caponiers. The fort was one of the distinctive new designs of the 1860s, which emphasised the provision of maximum protection for the guns and their detachments and new arrangements for the storage of ammunition under the emplacements and its supply to the guns via lifts.
Construction continued until the first year or two of the 1870s, soon after which the fort was armed. During building, the stench from nearby marsh ditches was said to be injurious to the health of the officers supervising the project. At this period, the Thames marshes were malarial and this might well have affected the workforce. Except for the presence of troops from various units visiting to practice gun drill or to take part in exercises, the fort was usually manned by a small caretaker garrison.
As an additional defence, provision was made to flood the marshes with river water by breaching the flood defence walls. This was to create an obstacle to the movement of an enemy landing force attempting to advance inland. By the later 1880s, the ditch of the fort had been infilled. This was to provide a further thickness of protection against incoming shells for the magazines, whose front wall was the escarp of the ditch. In the 1890s the front of the fort was adapted for the installation of the innovative new wire-guided Brennan Torpedo, added for river defence. In a practice firing it mistakenly sank a fishing boat which happened to be sailing by at the time.
Towards the end of the 19th century the rifled muzzle loaders with which the fort was armed had become obsolete in the face of the emergence of a more effective new weapon system based on use of the new, more rapid-firing breech-loaders. The muzzle-loaders were retained until the first few years of the 20th century but in the 1890s had been supplemented with the mounting of four 12-pounder quick-firing guns on the roof of the fort. In addition, searchlights were built outside the front of the fort. These would not only have illuminated the river at night for the firing of the guns but for the use of the Brennan Torpedo as well. The combined armament of heavy rifled muzzleloaders and light quick-firers was intended to defend against the attack of cruisers and torpedo boats. On withdrawal of the muzzle-loaders, the role of the quick-firers was to support and defend a river minefield expected to be provided in war on a line north across the Thames to East Tilbury. The 12 pounders constituted a light armament, but the heavier gun upgrading of the outer line of defence had been provided instead at East Tilbury, with a better command of the river approaches.
Disarmed by 1912, Cliffe Fort was rearmed with heavier weapons during the First World War against the German threat (2 x 6-inch breech-loaders, these being changed either near the end of the war or postwar to 4-in. guns). These guns would again have enabled the fort to engage cruisers, destroyers and any smaller enemy vessels. By 1927, and probably before, the fort was again armed with 6-in. weapons, which were presumably soon withdrawn as no armament is listed in a War Office report of 1934.
During the Second World War, the fort seems not to have been armed with heavy weapons and mainly to have served as a patrol base for part of the Royal Navy Auxiliary Service. South across the river from East Tilbury towards Cliffe Fort a line of sensors was laid on the seabed, to test that outgoing ships been desensitised (degaussed) against the threat of the deadly German magnetic mine. Should a ship which had failed its test neglect to stop on being advised to go to Tilbury Docks for remedial works to be carried out, one of the Royal Navy vessels at Cliffe Fort would be signalled to intercept.
The fort was also a Battle Headquarters for one of two groups of the Home Guard at Cliffe. In the post-war period the fort was for a time used as the headquarters of the Blue Circle Industries sailing club, following which it was abandoned to become derelict and vandalised.
On a rise about 300m NE of the fort, and on the south edge of Cliffe Creek, are the remains of a slit trench. This is presumably a local defence dating from either the First or the Second World War. It is likely to have been positioned to help defend Cliffe Creek which at high tide offered a tempting point of embarkation for an enemy landing force. This inlet had the added advantage of the availability of several dry routes from it which an enemy might take to advance inland. The trench may have been an element of a number of defences for this vulnerable point, including a possible boom defence. During the Second World War, searchlights were positioned on either side of the entrance to the Creek, although their former existence has left no obvious remains.
Lower Hope Battery
Further downstream, 1.2 km from Cliffe Fort, and as part of the evolving defense plans for the Thames, in the 1890s a small battery of 2 x 12-pounder quick-firing guns with flanking searchlights was built at Lower Hope. In 1904, the battery was described as supporting an Examination Line for shipping, which ran across the river from it to the north. The use of the battery’s searchlights for training purposes in the later 1890s and first few years of the 20th century was a cause for complaint for the masters of ships using the Thames, who were sometimes so dazzled by the powerful lights that they were unable to navigate and therefore were in danger of running aground or colliding with another vessel. The battery is not listed as being armed in documents of the First World War but eyewitnesses refer to the continued existence of the battery superstructures until the late 1920s or early 30s. The former existence of the battery is shown firstly by the remains of concrete bases on the river side of the sea wall and secondly by a section of the rear ditch of the battery on the landward side.
In the inshore river mud about 450 m SW of Cliffe Fort are the remains of the concrete bases of one of the Second World War anti-aircraft gun towers which had been uplifted and removed there from the waters of the Nore in the estuary in 1960. These gun towers had been highly innovative in their concept, having been constructed in 1942 on hollow concrete pontoons at the Red Lion wharf at Northfleet, to be towed downstream to the estuary, where their pontoons were flooded to lower them to a resting place on the seabed, leaving the guns and their platforms above the water, ready for firing.
by Victor Smith