FORTRESS TONBRIDGE
A German Tiger tank breaks out into the High Street, could this have happened?
At 4:35am on the morning of Friday 10th May 1940 German troops crossed the borders of the Netherlands, Belgium and Luxembourg. The second great war of the 20th Century had begun.
The German army were to pull off one of the most spectacular invasions the world had ever seen by using new technology, weapons and tactics or to give it the collective name that this method of mechanised warfare would later to be known by, “Blitzkrieg”; Lightening War.
Just 30 days later at a little seaside town called Les Petites – Dalles just 15 kilometres up the French coast from Fécamp, those same victorious German troops were dipping their toes in the English Channel.
France to, had succumbed.
Over the last days of May 1940 the miracle of Dunkirk had repatriated thousands of exhausted British troops and amidst the clearing air it was clear that Britain now stood alone. Nothing could possibly stop the German army from marching on London within weeks.
It was increasingly clear then that an invasion upon the south coast of Britain was imminent and Whitehall even began to question why Hitler was making us wait. But this respite bought us time and a hastily set up plan was introduced to build defenses in both Sussex and Kent that might if we were lucky stop him or at worst, slow him down. The south coast was fortified with anti tank defences, pillboxes and machine gun posts. Inland every waterway was defended by pillboxes and road blocks established at main road interchanges. Road signs were taken down and anti glider poles erected in the fields. Troops were conscripted and underground HQ bases built and manned; we were “almost” ready.
The German army were to pull off one of the most spectacular invasions the world had ever seen by using new technology, weapons and tactics or to give it the collective name that this method of mechanised warfare would later to be known by, “Blitzkrieg”; Lightening War.
Just 30 days later at a little seaside town called Les Petites – Dalles just 15 kilometres up the French coast from Fécamp, those same victorious German troops were dipping their toes in the English Channel.
France to, had succumbed.
Over the last days of May 1940 the miracle of Dunkirk had repatriated thousands of exhausted British troops and amidst the clearing air it was clear that Britain now stood alone. Nothing could possibly stop the German army from marching on London within weeks.
It was increasingly clear then that an invasion upon the south coast of Britain was imminent and Whitehall even began to question why Hitler was making us wait. But this respite bought us time and a hastily set up plan was introduced to build defenses in both Sussex and Kent that might if we were lucky stop him or at worst, slow him down. The south coast was fortified with anti tank defences, pillboxes and machine gun posts. Inland every waterway was defended by pillboxes and road blocks established at main road interchanges. Road signs were taken down and anti glider poles erected in the fields. Troops were conscripted and underground HQ bases built and manned; we were “almost” ready.
A German invasion map showing where the landing thrusts would fall; annotated with the place names by ourselves.
The military minds laid plans for a series of “stop lines”. It was likely that we would not be able to prevent a full scale coastal invasion by determined troops supported by hundreds of tanks and paratroopers dropped by the thousand. They would after all be supported by heavy artillery and the Luftwaffe’s dive bomber units already proven on the battlefields of Poland and Belgium. We were mindful of the fact that the immense and costly Maginot Line built by the French in 1932 to prevent aggression from the Germans on their eastern border and on which so much faith had been put, had been simply bypassed by the rapid Blitzkrieg advance.
Stop lines then, would be the answer; let the Germans in, let them get established on the ground and then build a series of strong linear defences increasing in complexity as they neared London. Muster our forces on these lines and stop them there. The south of England was to become one huge battlefield and a desperate one at that.
But still the Germans waited; waiting for the air supremacy over the RAF that they desperately needed before the Luftwaffe could take free rein of our skies and pound us into submission.
Geographically it looked like Kent would take the brunt of the fighting. All the major arterial roads to London passed through the county with one town in particular standing out as significant for it sat on both a navigable water way and on a gateway through the North Downs that commanded London.
Stop lines then, would be the answer; let the Germans in, let them get established on the ground and then build a series of strong linear defences increasing in complexity as they neared London. Muster our forces on these lines and stop them there. The south of England was to become one huge battlefield and a desperate one at that.
But still the Germans waited; waiting for the air supremacy over the RAF that they desperately needed before the Luftwaffe could take free rein of our skies and pound us into submission.
Geographically it looked like Kent would take the brunt of the fighting. All the major arterial roads to London passed through the county with one town in particular standing out as significant for it sat on both a navigable water way and on a gateway through the North Downs that commanded London.
Tonbridge High Street looking north from the bridge. This was to be the southern gate of the fortress.
Tonbridge had been designated a Nodel point, in military terms it meant that the defence of the county could be swung on this one geographic point. So in the later months of 1940 with the invasion long overdue, plans were drawn up at top level to fortify the town thereby creating “Fortress Tonbridge”.
Tonbridge was no stranger to the defence of the realm for its castle built some 900 years earlier by William the Conqueror, had been well placed on the banks of the River Medway strategically overlooking the whole town. In 1940 as of today, the main street ran North - South and offered a defendable gateway with the river dividing the town in two and traversed by an iron bridge that could be blown. The small narrow streets would be difficult for tanks to manoeuvre and close quarters street fighting would inevitably lead to a slowing up of the German advance. With all this in mind, an iron curtain was to be sited around the town and garrisoned within by determined soldiers and the German advance on London halted.
Tonbridge was no stranger to the defence of the realm for its castle built some 900 years earlier by William the Conqueror, had been well placed on the banks of the River Medway strategically overlooking the whole town. In 1940 as of today, the main street ran North - South and offered a defendable gateway with the river dividing the town in two and traversed by an iron bridge that could be blown. The small narrow streets would be difficult for tanks to manoeuvre and close quarters street fighting would inevitably lead to a slowing up of the German advance. With all this in mind, an iron curtain was to be sited around the town and garrisoned within by determined soldiers and the German advance on London halted.
A Bofors anti-aircraft gun defending the western flank playing fields
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A Vickers machine gun pit at Portland Park
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The Map and Methods of Defence.
The defensive map of the town shown here is dated December 1941 and is probably a much modified version taking into account the changing direction of the war. By this time Hitler had moved his attention to Russia and Britain had endured the Blitz and perhaps more importantly, America was about to enter the war. So this map was probably out of date. However its detail is well worth studying and offers an insight into the military mind at work.
The defenses of the town are arranged as such:
1) Concrete anti tank obstacles would be erected around the town and built into existing buildings to form a long circular perimeter wall.
2) 3 pillboxes were to be built, 2 at either end of the high street and the third located to the west of the town in the corner of the school playing fields. This would cover the new western flank anti tank ditch.
3) Socketed obstacles would be placed in the narrow streets to stop enemy tanks and armoured cars approaching from the cover of buildings.
4) 19 road blocks would be established all around the perimeter roads of the town effectively sealing up any gaps in the outer defensive wall. Important pillbox protected road blocks were to be established at the north and south junctions of the high street; in effect closing the town gates.
5) The Mill Stream tributary of the river Medway to the east of the town and the smaller reach of the Medway next to the Castle’s southern mound would be deepened to prevent fording by enemy troops and tanks.
6) To protect both flanks east and west; anti tank ditches would be dug and a barbed wired killing ground established a few hundred yards away from the town’s perimeter defensive walls.
7) All of these solid defences were then to be protected by 11 weapon pits to be established in either existing buildings or dug specially into the ground. There would be one large weapon pit emplacement at the corner of Mill Stream and the River Medway by the town lock giving a 360 degree angle of fire.
Each weapon pit would have been fitted with mortars, Blacker Bombards (29mm spigot mortars), heavy machine guns or 2 pdr (40mm) anti tank guns as deemed necessary.
The defensive map of the town shown here is dated December 1941 and is probably a much modified version taking into account the changing direction of the war. By this time Hitler had moved his attention to Russia and Britain had endured the Blitz and perhaps more importantly, America was about to enter the war. So this map was probably out of date. However its detail is well worth studying and offers an insight into the military mind at work.
The defenses of the town are arranged as such:
1) Concrete anti tank obstacles would be erected around the town and built into existing buildings to form a long circular perimeter wall.
2) 3 pillboxes were to be built, 2 at either end of the high street and the third located to the west of the town in the corner of the school playing fields. This would cover the new western flank anti tank ditch.
3) Socketed obstacles would be placed in the narrow streets to stop enemy tanks and armoured cars approaching from the cover of buildings.
4) 19 road blocks would be established all around the perimeter roads of the town effectively sealing up any gaps in the outer defensive wall. Important pillbox protected road blocks were to be established at the north and south junctions of the high street; in effect closing the town gates.
5) The Mill Stream tributary of the river Medway to the east of the town and the smaller reach of the Medway next to the Castle’s southern mound would be deepened to prevent fording by enemy troops and tanks.
6) To protect both flanks east and west; anti tank ditches would be dug and a barbed wired killing ground established a few hundred yards away from the town’s perimeter defensive walls.
7) All of these solid defences were then to be protected by 11 weapon pits to be established in either existing buildings or dug specially into the ground. There would be one large weapon pit emplacement at the corner of Mill Stream and the River Medway by the town lock giving a 360 degree angle of fire.
Each weapon pit would have been fitted with mortars, Blacker Bombards (29mm spigot mortars), heavy machine guns or 2 pdr (40mm) anti tank guns as deemed necessary.
The Fortress Tonbridge Map Dated December 1941
When complete, the area around the Church to the east of the high street; extending south to East Street and north to Portman Park with its eastern wall running along Hadlow Road and its western wall running the length of the high street; would have been one large Redoubt populated by the defending army.
The wartime fortress map overlaid onto a modern map for comparison
Would it Have Worked?
I believe the answer to this question lies solely with the concept of air supremacy. If tactical mistakes made by the German's early on in the Battle of Britain had not been made and the Luftwaffe had succeeded in overpowering the RAF by the relentless bombing of our airfields then they would have had full control of the airspace over Britain. That would have allowed vast parachute drops of men and equipment and mass dive bombing attacks on all fortified areas in southern England. In this instance Fortress Tonbridge would not have had a chance and would have quickly capitulated under this massive onslaught. Sadly, no doubt reducing the town of Tonbridge to ruins!
I believe the answer to this question lies solely with the concept of air supremacy. If tactical mistakes made by the German's early on in the Battle of Britain had not been made and the Luftwaffe had succeeded in overpowering the RAF by the relentless bombing of our airfields then they would have had full control of the airspace over Britain. That would have allowed vast parachute drops of men and equipment and mass dive bombing attacks on all fortified areas in southern England. In this instance Fortress Tonbridge would not have had a chance and would have quickly capitulated under this massive onslaught. Sadly, no doubt reducing the town of Tonbridge to ruins!
A light Stuart tank defending the northern gate to the fortress
To be heavily defended - the Town Lock on the river Medway could have been the scene of bitter fighting
But of course the actual events that took place made the plans for the Fortress redundant by June 1941 as the invasion threat subsided and thankfully it was never to be tested in anger, so we will never know how effective Fortress Tonbridge would have been at stopping the might of Hitlers warriors!
Maps: National Archives, Kew.
Copyright Steve Sullivan, January 2022
Maps: National Archives, Kew.
Copyright Steve Sullivan, January 2022
