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The Defence of Kent


Victor Smith



The remains of the fortifications in stone, brick, earth and steel along the Kentish coast and inland are reminders of an era when Britain and her Continental neighbours settled their differences by force of arms.  They symbolise a determination to safeguard England’s freedom against foreign aggression.  Yet they were also a consequence of needing to protect against the reaction of states with which were in competition, either for political dominance, control of trade or the acquisition of colonies abroad.  But the forts and batteries of Kent were only part of the means of defence, which included field armies when invasion threatened and the fleet at sea, Britain’s first line of defence


Geographical factors

The seas around Britain were both a defensive moat and a vulnerability, providing a means for ships to reach and raid our coastline or land troops in an invasion.  Kent was most at risk, being closest to the Continent via the short sea crossing of the English Channel.  But by the 20th century the Channel could be over flown by aeroplanes to drop their bombs on Kentish and other targets in Britain. 


In the north of the county the Thames trading route to London penetrates deeply inland and needed protection, as did the Medway containing from the 17th century important naval bases, and Dover considered the ‘Key to England’.  There were other smaller ports and inlets to defend as well as the lines of beaches in south Kent suitable for a landing, either side of the rampart of high chalk cliffs.


The influence of technology

Defences expressed the development of new technology as applied to war, both in relation to the weapons used and techniques of construction for building of structures that housed them.  They are a story of thrust and counter-thrust, with the need for new defensive measures to respond to innovations in attack.  The key milestones in this journey began with the move from the drawn bow, edged weapons and catapults to gunpowder firearms, and their refinement following the Industrial Revolution.  Then came the invention of aeroplanes, the long-range war rocket and the nuclear weapon.


Pre-Roman and Roman defences

Fortified earth and timber enclosures and hillforts, both in coastal areas and inland were established in the Iron Age, both for protection of individual communities against clan or tribal threats or as defended political centres forming part of broader tribal confederations. Examples of these can be seen at Oldbury and Bigberry hillforts.


The fortifications of earth, timber or stone introduced during the Roman invasions and occupation were the tools of an organised state, at first in support of campaigns of invasion and conquest, as at Richborough with remains of the beachhead from the invasion of AD 43.  Later fortifications were instruments of imperial defence, supported by a Roman fleet in coastal waters.  As part of a system of coastal defence, distinctive new fortifications were established from the later 2nd and third centuries at Reculver, Richborough, Dover and Lympne. Inland, Canterbury and Rochester  were fortified.

Richborough Fort

Image: Richborough Roman Fort


Early Medieval

The nature, purpose and ownership of the defences established or re-used in the 650 years after the Roman occupation were determined by a sequence of political and military circumstances and the ebb and flow of territorial acquisition and control.  This spanned the period of independent or semi-independent status for Kent, followed first by assimilation into Mercia and finally complete absorption into Wessex.


Norman-14th century

The fortifications of the invading Normans asserted the power and authority of the new regime and control over the estates by individual lords. They were badges of feudalism which rewarded loyalty and the promise of military service to the Crown with awards of land and privileges.  These were earthen and timber motte and bailey and ringwork castles, at various sites along the coast, with others inland along important roads, road intersections in towns and river crossings.  Towns were also fortified. The town walls of Dover, Canterbury and Rochester were refurbished and strengthened and earth ramparts built around Sandwich and Tonbridge.


Even in the 12th century some castles were still built of earth and timber but increasingly stone was used.  Many examples of these castles survive today such as the great castles of Dover, Rochester, Canterbury and Tonbridge and the smaller castles such as at Thurnham, Sutton Valence  and Eynsford. More information on these can be seen in the accompanying section on Kent’s Castles.


Castles and cannon

From the later 14th century and during the Hundred Years War with France when French raiding occurred, the influence of the introduction of gunpowder and of firearms on defensive architecture is clear to see in the display of key-hole and circular gunports at Cooling, Saltwood and Dover castles as well as in Canterbury’s Westgate and town walls.  All otherwise manifest the building traditions of the medieval period with high and monumental stone walls.  The innovative concentric Queenborough Castle  was provided with firearms and in the 15th century gun loops were provided at Hever castle and in the 16th century at Shurland Hall , with artillery defences at Sandwich.

 Cooling Castle, Cooling

Image: Cooling Castle


New weapon systems from the early-16th century

From the 1520s and 30s the growing effectiveness of artillery meant that guns could fight an action with enemy ships at long range.  Defences to mount them were designed around the use of artillery in purpose-made emplacements.   In the 1520s gun towers were built to defend Dover harbour.  More distinctive were Henry VIII’s multi-round bastioned forts guarding the Downs anchorage at Walmer, Deal and Sandown forts.  Others were added at Dover, the lower Thames and the Medway.

 Deal Castle from the beach

Image: Deal Castle from the beach


The angular bastion in the mid-16th to 17th centuries

A new system of defence was introduced from the Continent based on the use of angular bastions placed at intervals in a defensive circuit to fire on all the ground in front of a fortification.  Single bastions were added to the Milton Blockhouse at Gravesend in 1547 and provided for  the new Upnor Castle in the Medway in 1559 but around 1600 a front of two angular bastions and a curtain were incorporated within Archcliffe Fort at Dover.  It was this form which guided the design of the extensive fortifications constructed at Sheerness, following the Dutch Raid of 1667, when other batteries were built upstream at Cockham Wood and Gillingham.


Reaction to Continental Wars in the 18th century

The 18th century opened with a succession of French invasion scares but no serious new work of fortification was undertaken until 1755 when Dover castle was massively altered to make it a fully-fledged artillery fortress, and a line of angular bastions was formed to defend the landward approaches to Chatham dockyard .  In the 1770s during the American War of Independence, Dover  was protected with new batteries at harbour level with massive earthworks on the Western Heights .  New bastioned lines were also made at Sheerness, forts built in the Thames and at Broadstairs and Margate.


The French Wars 1793-1815

During the French Revolutionary and Napoleonic Wars, Britain faced invasion by forces of unprecedentedly large size. Countermeasures had to be proportionate.  Undertaken in phases, these involved fortifying whole lengths of the county’s coast and hinterland.   Most vividly this was expressed in the great Martello Tower programme and the cutting of the Royal Military Canal .  Numerous batteries were built at harbours and along the coast from Thanet to Dungeness, with a massive expansion of the fortress on the Western Heights at Dover.  At Chatham, forts Pitt and Clarence defended the approaches to the bridge crossing of the Medway at Rochester and new batteries were built to guard the entrance to the Thames at Shornemead and Lower Hope .  Many were armed with guns on the innovative traversing platform which allowed them to be turned rapidly on target.

 The Drop Redoubt, Dover Western Heights

Image: The Drop Redoubt, Dover Western Heights


After the Napoleonic Wars

Further invasion scares followed the Napoleonic Wars in 1825 and 1830, but without leading to much new construction.  A scare of 1847 led to the building of the innovatory new Shornemead Fort (1848-52) which introduced to Kent the new polygonal style of fortification, with its more effective division of defensive fire.  Also built was the slightly retrograde Martello tower at Grain (1855).  Both now faced the challenge of  attack from the new fast-moving steam powered French warships.


The weapon systems of the industrial age

In the 1860s Kent shared in a massive new national scheme of defence construction.  This was a reaction to a perceived challenge from the France of Napoleon III and her building of the new weapons of the industrial age: the steam ironclad warship armed with dramatically more powerful and longer range rifled muzzle-loading guns.  Reinforcing a British programme to build a new ironclad fleet the coastal defences were modernised to mount rifled guns on mechanical carriages.  In the Medway and the Thames they were protected in granite-faced and armoured forts at Garrison Point, Darnet and Hoo and in the Thames at Coalhouse Point, Cliffe and Shornemead as well as at Slough Fort at Allhallows.  There were other new batteries in the Thames at Gravesend and in the Medway at Grain.  An advanced defence, Queenborough Lines  was built behind Sheerness.  At Dover new batteries were built on the castle Cliffs and the Western Heights defences were massively extended.



The high point of the muzzle-loading age was the building in 1878 of the rotating and armoured Dover Turret on the Admiralty Pier.  But technology advanced again and muzzle-loaders were succeeded by faster-firing breech-loading guns between the 1890s and 1905.  With sophisticated new range-finding, command and control systems, telephone communication and electric searchlights, these weapons were mounted in new emplacements in the Thames and Medway and at Dover.  Also responding to progress in weaponry, a new advanced front of defences protecting the land approaches to Chatham was created.  This was to be defended by a movable armament.  To the south and east of London, a contingency plan was created for entrenching the North Downs against an invader advancing overland to the capital.  In preparation, defensible positions were built in peace time, with pre-positioned supplies of ammunition and tools.  Within Kent, these were at Farningham, Halstead  and Knockholt. 


The First World War

The reduction of tensions with France following the Entente of 1904, left Imperial Germany as the likely future enemy and potential invader.  Defensive preparations were made with that in mind.  The fundamental new technological challenge of the First World War was a new form of attack – from the air by airships and bomber aeroplanes.  A whole new type of defence was evolved: ground observers and sound locators to warn of an attack, interceptor air craft based at Eastchurch, Detling, Manston, Dover and elsewhere, backed by anti-aircraft guns and searchlights, especially at Dover, Chatham, Chattenden and Sheerness.  There is a rare surviving battery at Lodge Hill. Along the coast the batteries built in the 1890s were activated and new ones built, including the surviving Fletcher Battery on Sheppey.  Inland there were various anti-invasion ‘stop-lines’ of trenches – between the Swale and Maidstone, around Chatham, along the edge of the North Downs at various points, including Sevenoaks and Westerham, with another line along the north shore of Sheppey.



After the First World War, there was no identifiable enemy and defence forces were rapidly reduced.  But air and naval forces were to be built up again to achieve a balance of power with France, not that war with that country was envisaged.  There was a falteringly progressed scheme to increase the number of operational air defence squadrons and a network of aircraft ground observers was recruited from 1925.  Building on experience of the First World War, semi-experimental concrete sound mirrors were built to warn of the approach of French warplanes, with surviving sites at Abbots Cliffe , Hythe and Greatstone.  But Germany emerged as the real potential enemy and from 1937 radar long-range detection replaced permanent sound locators, with sites remaining at Dunkirk and Swingate.  The airfields were expanded with key sites at Eastchurch, Hawkinge, Detling and Manston, and new anti-aircraft batteries were built.  At the same time, a new organisation of civil defence was created to protect communities and infrastructure from the result of air bombing, expected to be experienced in any war with Germany, the use of gas bombs as well as high explosive being feared. During the Munich Crisis of 1938 British armed forces were put on alert and trench shelters were cut in many parts of Kent.


The Second World War

When war with Germany was joined in 1939, allied containment of German forces by Franco-British deployments on the Continent made the possibility of invasion seem unlikely.  But the defeat of the allies in June 1940 and the evacuation from Dunkirk focussed attention on the need for anti-invasion measures.  This led to the creation of a defence scheme based on a ‘coastal crust’ of pillboxes and gun batteries, with the ports of Dover, Medway and the Thames, being given particular attention, backed by a succession of other defences inland.  The latter included ‘stop lines’ of pillboxes, road blocks and anti-tank ditches across the countryside and the encirclement of road junctions in towns and villages with defences, all intended to impede the advance of enemy tanks and infantry and to channel him into ‘killing fields’ and prepared battlefields.  The countryside was also obstructed with obstacles against the landing of German gliders and troop-carrying aeroplanes.  Good examples of inland defences can be seen along the left bank of the Medway and across the Hoo Peninsula to Cliffe, as well as along the Royal Military Canal. 

 Vickers machine gun post south of Teston

Image: Vickers machine gun pillbox, Teston


But it was air attack rather than invasion which Britain and Kent had to face, through painful experience, beginning with the Battle of Britain in the Autumn of 1940.  In expectation of this, the interwar programmes for building anti-aircraft batteries and fighter airfields as well as for establishing ground observer posts, had been accelerated, with a network of batteries built to cover the industrial and military infrastructure of the Thames and Medway as well as the port of Dover.  Other batteries were built near various towns.  Many further batteries were added and relocated for the DIVER programme of 1944 to defend against V1 attacks on Britain.  Airfields were added at West Malling and elsewhere, including emergency landing grounds.  As important  was the system of target detection and coordination of the air defences which had been evolved.  Part of this was an enhancement of radar, down to tactical level for individual anti-aircraft batteries.


A corollary of this, was the need also to enhance civil defence which, like air defence, had been started before the outbreak of war.  Most effort was in 1939-40, with the completion of the infrastructure of air raid wardens posts, first aid posts, gas decontamination centres, bases for rescue units and control centres for coordinating civil defence.  At the same time,  there was extensive construction of air raid shelters, both as surface blockhouses and cut and cover underground systems.  In some towns, including Rochester, Northfleet, Ramsgate and Dover, there were large chalk tunnel air raid shelters, which still exist.  Alongside these were the ubiquitous government-issued corrugated iron Anderson Shelters still to be found in some back gardens and the metal table-like Morrison shelter, in homes..


In 1944, Kent took part in the preparations for Operation Overlord, to liberate Continental Europe.  These included the establishment of further airstrips, Pipeline Under the Ocean (PLUTO) to supply the allied armies with fuel for vehicles, several embarkation hards along the coast and rivers the formation of the deception scheme Operation Fortitude South, to convince Germany that the allies would be landing through the Calais area and not Normandy, the real destination.


The Cold War

Peace in 1945 gave only a short respite, as from 1946  came the Cold War and, soon the prospect of attack with nuclear weapons.  So from 1947/8 steps were taken to re-form the anti-aircraft and coastal defences, (and from 1950 to build ground aircraft observation posts) as well as to re-create an organisation of civil defence.  The latter centred on a War Room at Tunbridge Wells, with a county control at Maidstone and other local controls in towns, along with the reviving of wardens posts and rescue centres.  There was no revival of shelter protection but people were advised how they could protect themselves at home.  In 1960 a Regional Seat of Government was created at Dover.  At the same time, the surface observer corps posts were exchanged for bunkers underground from which the occupants were to monitor and report nuclear explosions and radioactive fallout.  In 1968 civil defence was abandoned to cut costs but was revived in  a lesser way in the 1970s and 80s, and finally ended in 1989/90 at the end of the Cold War.   Some ground observation posts and underground monitoring bunkers survive, together with the Regional Seat of Government at Dover and among the local control centres, one at Gravesend which is open to visitors.