The Six Inch Gun Battery
at Castle Hill
+Friars Bay Radar Station & 3.7in Protective AA Battery
The Port of Newhaven on the East Sussex coast had once enjoyed a prosperous career as a busy gateway to the continent. Served by railway and frequent channel crossing ferries it had been the quickest and most accessible method for the Londoner to embark upon a continental holiday in the years before the second world war. The railway junction at Newhaven Port even had its own comfortable hotel right by the ferry departure point at the harbour. It was clearly an important Channel port and as such its defence would be an important priority at the outcome of the war. However, as in the case of most of Britain in 1939, these defences were woefully inadequate; a fact bordering on the ridiculous with the threat of the German 9th Army landing at Seaford Bay.
Though the Victorian fort had offered some defensive prospect it had lain dormant since the Great War and its armament was at best obsolete though workable and at worst simply hopeless against preventing a German full scale invasion of the port.
In 1939 the fixed defences at Newhaven, sited mainly in the fort itself were as follows:
This decision lead to the building of a modern coastal gun battery far exceeding in efficiency anything else on the southern coast bar those at Dover. This new battery was to use the more powerful Mk 24 6 inch gun supported by Defensive Search Lights, a Directional Range Finder, a fully updated Observation Command Post, a dedicated Battery Plotting Room and Radar Controlled Predicted Range Finding.
There would be three 6 inch guns on purpose built fully camouflaged mountings complete with integral magazines, power houses and crew quarters with each gun capable of 180 degrees of traverse and 45 degrees of elevation, the latter giving ranges exceeding 25,000 yds; some 15 miles out to sea which is the full distance to the horizon from the intended location point. This new battery was to greatly enhance the defence of the Port by stopping any enemy vessel regardless of size, from attempting to make an aggressive approach, day or night upon Newhaven harbour.
Though the Victorian fort had offered some defensive prospect it had lain dormant since the Great War and its armament was at best obsolete though workable and at worst simply hopeless against preventing a German full scale invasion of the port.
In 1939 the fixed defences at Newhaven, sited mainly in the fort itself were as follows:
- For close defence: Two 6 inch guns mounted on the southern ramparts of the fort battlements. This was known as the day and night “Examination Battery” with the job of engaging any vessels entering the bay that did not respond to the harbour masters call for identification.
- For anti MTB defence: Two 12 pdr guns mounted on the fort ramparts and only capable of engaging targets at closer range than the 6 inch guns.
- A close defence battery situated at midpoint and overlooking Seaford Bay adjacent to the old Tide Mills. These were two Naval 6 inch guns on hard standing mountings and were emplaced to support the two 6 inch guns at the Fort. They would not be allowed to engage targets at ranges greater than 6,000yds.
- There was also a 3 pdr Naval gun mounted in reserve at the eastern side of the fort and was to be used for beach defence only.
This decision lead to the building of a modern coastal gun battery far exceeding in efficiency anything else on the southern coast bar those at Dover. This new battery was to use the more powerful Mk 24 6 inch gun supported by Defensive Search Lights, a Directional Range Finder, a fully updated Observation Command Post, a dedicated Battery Plotting Room and Radar Controlled Predicted Range Finding.
There would be three 6 inch guns on purpose built fully camouflaged mountings complete with integral magazines, power houses and crew quarters with each gun capable of 180 degrees of traverse and 45 degrees of elevation, the latter giving ranges exceeding 25,000 yds; some 15 miles out to sea which is the full distance to the horizon from the intended location point. This new battery was to greatly enhance the defence of the Port by stopping any enemy vessel regardless of size, from attempting to make an aggressive approach, day or night upon Newhaven harbour.

Above Left: A Mk 7 6 inch gun in a much lighter mounting.
Above: Home Guard members practice with one of the
Mk7 6 inch close defence guns at Fort Newhaven
in 1942.
Left: An over stylised depiction of coastal guns in
position on the south coast drawn for the Illustrated
London News in July 1940.
Above: Home Guard members practice with one of the
Mk7 6 inch close defence guns at Fort Newhaven
in 1942.
Left: An over stylised depiction of coastal guns in
position on the south coast drawn for the Illustrated
London News in July 1940.
Work Commences
Today, a pleasant walk maybe had taking the footpath from Newhaven Fort up towards the Coast Guard watch station on Castle Hill and onto the caravan park before Peacehaven Heights. On the approach to the Coast Guard Station one cannot miss the remains of this once magnificent gun battery with its command of the sea beyond; for it was perfectly located for the job it had to do.
Work was commenced in November 1941, being executed by both R.E. Construction Company and Civilian Contractors. The work was completed by February 1943 and handed over to the R.A. in June 1943. Two months later in August 1943 all three guns were test fired as fit for use and handed over to 100 Coast Battery, 521 Coast Regt. R.A. This unit was relieved in September 1943 by 193 Coast Battery R.A. from Yorkshire who manned it for the remainder of the war.
The battery was finally placed on a Care & Maintenance basis from October 1944 having only served for 13 months, shorter than the time it took to build it. Number 1 gun was removed in October 1949 and the remaining two certainly by the early 1950’s when the site was abandoned to the elements. As far as our research has shown the battery never fired a shot in anger during its short tenure.
Today, a pleasant walk maybe had taking the footpath from Newhaven Fort up towards the Coast Guard watch station on Castle Hill and onto the caravan park before Peacehaven Heights. On the approach to the Coast Guard Station one cannot miss the remains of this once magnificent gun battery with its command of the sea beyond; for it was perfectly located for the job it had to do.
Work was commenced in November 1941, being executed by both R.E. Construction Company and Civilian Contractors. The work was completed by February 1943 and handed over to the R.A. in June 1943. Two months later in August 1943 all three guns were test fired as fit for use and handed over to 100 Coast Battery, 521 Coast Regt. R.A. This unit was relieved in September 1943 by 193 Coast Battery R.A. from Yorkshire who manned it for the remainder of the war.
The battery was finally placed on a Care & Maintenance basis from October 1944 having only served for 13 months, shorter than the time it took to build it. Number 1 gun was removed in October 1949 and the remaining two certainly by the early 1950’s when the site was abandoned to the elements. As far as our research has shown the battery never fired a shot in anger during its short tenure.
The plans above show clockwise form top left: The defence plan for the fort and guns showing weapon pits and search light locations. The layout plan for the gun mountings showing shell and cartridge recess allocations. The scheme of camouflage plan for all three guns. The erosion and ground plan for all three guns; all circa 1943.
Constructional Details
The work consists of three emplacements for the Breach Loading Mk24 6 inch gun on B.L. type Mk 5 or 6 mountings with enclosed armoured steel shields around each gun. All emplacements are of similar construction of re enforced concrete with overhead covering supported by steel girdering. To each emplacement there is a Gun Store, Watch Shelter, Separate Shell and Cartridge Stores and a Cable Room for electric power distribution and control. There are also 5 shell and 5 cartridge recesses, capable of holding a total of 125 Shell and 125 Cartridges. All doors and shutters are of steel. All emplacements were to be elaborately camouflaged from aerial observation.
The distance between No.1 and No.2 guns is 70 yds and that between No.2 and No.3 guns is 95 yds. Height above sea level is on average 170ft giving a visible horizon range of 15 miles, the exact maximum range of the guns.
The Battery Plotting Room (BPR) is situated to the rear of No.2 gun and accessed by a purpose built concrete foot path. It is built of re enforced concrete and sunk so that the roof is level with the surrounding ground. There was a latrine block at the top of the footpath rear of No.2 gun, now demolished.
The BPR also held the rectifiers and transformers for distributing the power to the gun emplacements from the 5 KW DC generating room housed in the forts western moat. All lighting ran off a 100 volt AC supply and this could also be fed by the national grid if required.
The Battery Observation Posts (BOP) were an essential part of any working defensive battery and can be said to be the eyes and ears of the whole set up. Newhaven had three; Firstly situated 2000 yds away to the right flank high up at 240ft above sea level (ASL) at Friars Bay was the Radar, Position Finder and Director Station that kept watch out to the horizon while scanning 180 degrees of sea area. This was the main BOP. Secondly there was the Close Defence and Night BOP situated in the extreme south western corner of the fort and thirdly attached to this placed slightly lower down on the cliff edge was the Directional Range Finder station which also controlled the Defence Electric Lights (DEL), search lights positioned around the port and bay areas; there were five of these at Newhaven and a further two positioned around Seaford Bay. Power for these was supplied by two further generating stations positioned around the harbour mouth area.
Finally the entire site was protected by two infantry posts based at either end of the lower harbour frontage and thick barbed wire fencing surrounding the fort and battery site where numerous weapon pits and strong points had been dug into the earth. The beach area to the west of the fort was also mined likewise that of Seaford Bay beach.
Newhaven Port was now a heavily defended area with a total of ten large guns pointing seaward and ready to challenge any enemy vessels that either strayed too close or tried to slip past while remaining far out at sea.
The work consists of three emplacements for the Breach Loading Mk24 6 inch gun on B.L. type Mk 5 or 6 mountings with enclosed armoured steel shields around each gun. All emplacements are of similar construction of re enforced concrete with overhead covering supported by steel girdering. To each emplacement there is a Gun Store, Watch Shelter, Separate Shell and Cartridge Stores and a Cable Room for electric power distribution and control. There are also 5 shell and 5 cartridge recesses, capable of holding a total of 125 Shell and 125 Cartridges. All doors and shutters are of steel. All emplacements were to be elaborately camouflaged from aerial observation.
The distance between No.1 and No.2 guns is 70 yds and that between No.2 and No.3 guns is 95 yds. Height above sea level is on average 170ft giving a visible horizon range of 15 miles, the exact maximum range of the guns.
The Battery Plotting Room (BPR) is situated to the rear of No.2 gun and accessed by a purpose built concrete foot path. It is built of re enforced concrete and sunk so that the roof is level with the surrounding ground. There was a latrine block at the top of the footpath rear of No.2 gun, now demolished.
The BPR also held the rectifiers and transformers for distributing the power to the gun emplacements from the 5 KW DC generating room housed in the forts western moat. All lighting ran off a 100 volt AC supply and this could also be fed by the national grid if required.
The Battery Observation Posts (BOP) were an essential part of any working defensive battery and can be said to be the eyes and ears of the whole set up. Newhaven had three; Firstly situated 2000 yds away to the right flank high up at 240ft above sea level (ASL) at Friars Bay was the Radar, Position Finder and Director Station that kept watch out to the horizon while scanning 180 degrees of sea area. This was the main BOP. Secondly there was the Close Defence and Night BOP situated in the extreme south western corner of the fort and thirdly attached to this placed slightly lower down on the cliff edge was the Directional Range Finder station which also controlled the Defence Electric Lights (DEL), search lights positioned around the port and bay areas; there were five of these at Newhaven and a further two positioned around Seaford Bay. Power for these was supplied by two further generating stations positioned around the harbour mouth area.
Finally the entire site was protected by two infantry posts based at either end of the lower harbour frontage and thick barbed wire fencing surrounding the fort and battery site where numerous weapon pits and strong points had been dug into the earth. The beach area to the west of the fort was also mined likewise that of Seaford Bay beach.
Newhaven Port was now a heavily defended area with a total of ten large guns pointing seaward and ready to challenge any enemy vessels that either strayed too close or tried to slip past while remaining far out at sea.
Performance of the Guns
Firing a 100 pound shell at 2857 fps when elevated to 45 degrees the guns had a maximum range of 25,100 yds or 14 ¼ miles. Shells were generally HE / AP and depending upon the target to be engaged the range could also be controlled by varying the propellant charge which was a caseless bagged charge that could either be ignited electrically or by a percussion cartridge. The shell was fused immediately before firing and would be selected for impact or timed delay actuation. The performance of these guns was such that if engaging a ship 15 miles away on the horizon it would take just 30 to 40 seconds for each shell to travel the distance required. Interestingly, the gun barrels were to be changed every six months by order regardless of whether they had been shot out or not; one wonders whether the rigors of their coastal environment took its toll on the barrel steel?
Firing a 100 pound shell at 2857 fps when elevated to 45 degrees the guns had a maximum range of 25,100 yds or 14 ¼ miles. Shells were generally HE / AP and depending upon the target to be engaged the range could also be controlled by varying the propellant charge which was a caseless bagged charge that could either be ignited electrically or by a percussion cartridge. The shell was fused immediately before firing and would be selected for impact or timed delay actuation. The performance of these guns was such that if engaging a ship 15 miles away on the horizon it would take just 30 to 40 seconds for each shell to travel the distance required. Interestingly, the gun barrels were to be changed every six months by order regardless of whether they had been shot out or not; one wonders whether the rigors of their coastal environment took its toll on the barrel steel?
Seaford Bay Defences as of 1944
The "Chart of Lights" map below shows the defensive layout for Seaford Bay shortly after the 6 in battery had been built. It clearly shows the location of the main guns and the excellent search light coverage that reached out some 4000 yds (2.5 miles) out to sea.
The "Chart of Lights" map below shows the defensive layout for Seaford Bay shortly after the 6 in battery had been built. It clearly shows the location of the main guns and the excellent search light coverage that reached out some 4000 yds (2.5 miles) out to sea.
Engaging a Distant Target
To better appreciate how this coastal battery would have operated we have here a speculative account of the procedures undertaken during an actual engagement of an enemy warship passing by Newhaven Port while traversing the English Channel. This information has been largely extracted from the “Fire Commanders Standing Orders”. Newhaven Fire Command R. A. Dated 24/3/1941. As of this date the Castle Hill Battery has not yet been built but the engagement procedure would have been the same albeit much more efficiently done using the new updated technology.
Firstly we will assume that an enemy warship has departed from Brest and is passing through the Bay of Biscay and heading north east towards Norway and the North Sea. The ship has strayed a little to close to the British coast and is picked up by the Friars Bay Radar Station and identified as hostile. The radar station calculates the range to the warship and plots its course, speed and bearing and marks this on the navigation charts available. The warship is plotted for a little while to assess if it is making any course changes either aggressively towards the English coast or defensively towards the French coast.
This information is relayed to the BPR behind No.2 Gun who’s crew further plot the progress of the warship and its distance from the gun battery.
The BPR informs the BOP at Fort Newhaven to see if their Directional (optical) Range Finder has a visual fix on the ship to verify the exact range from the guns. In our scenario we conclude that the target is just beyond visual range and the BPR are so informed. Further information is collected from the Radar Station and exact range, course and speed are updated to the BPR. The close defence guns are informed that they are not required and are stood down.
The BPR crew now issue the order to make ready the guns and shells are selected, fused and loaded into each gun along with a full propellant charge. The master gunners are issued with the known target co ordinates and are ordered to engage on command.
The guns are to fire a bracket salvo under the direction of the BPR as of; No.1 gun will fire slightly long in range, No.2 gun will fire as target predicted and No.3 gun will fire slightly short in range. Traverse, inclination, windage and deflection data are now applied to each gun by the master gunners.
All three guns are fired in quick succession while the BOP is instructed to spot the fall of shots where possible. The Radar Station crew now look for any changes in course of the target in response to the engagement. In our scenario we will say that all three shots miss; two fall short while one passes over the warship completely.
At this point the enemy warship will now dictate how the engagement will unfold. If the target ship changes course towards France it will be avoiding further action by increasing the range and the guns will “Stand To”. If the target ship remains steady on its course then the gun battery may well fire another warning bracket salvo at it with the appropriate range corrections made to tighten the bracket and perhaps anticipate that the warship may well fire a salvo in reply from its own heavy calibre main armament.
Lastly, the enemy warship might reduce the range by turning towards the English coast as an aggressive manoeuvre and threaten the coastal battery and port with further bombardment from its main armament; this action would undoubtedly result in both swift Allied Naval and Air Force intervention.
From our scenario it becomes clear that the six inch battery would have been woefully under powered to take on large warships should they be on aggressive manoeuvres against Newhaven Port. They would however have been perfectly capable of destroying smaller vessels such as MTB’s or Submarines should the need arise, far out at sea before the close defence guns would be required to protect the inner Seaford Bay area.
But in reality the construction of this battery was not about actual engagements at all. It was about its deterrent strength and as such it did indeed fore fill its role perfectly in protecting this part of the Sussex coast during the few short months before the war moved on towards its inevitable conclusion.
To better appreciate how this coastal battery would have operated we have here a speculative account of the procedures undertaken during an actual engagement of an enemy warship passing by Newhaven Port while traversing the English Channel. This information has been largely extracted from the “Fire Commanders Standing Orders”. Newhaven Fire Command R. A. Dated 24/3/1941. As of this date the Castle Hill Battery has not yet been built but the engagement procedure would have been the same albeit much more efficiently done using the new updated technology.
Firstly we will assume that an enemy warship has departed from Brest and is passing through the Bay of Biscay and heading north east towards Norway and the North Sea. The ship has strayed a little to close to the British coast and is picked up by the Friars Bay Radar Station and identified as hostile. The radar station calculates the range to the warship and plots its course, speed and bearing and marks this on the navigation charts available. The warship is plotted for a little while to assess if it is making any course changes either aggressively towards the English coast or defensively towards the French coast.
This information is relayed to the BPR behind No.2 Gun who’s crew further plot the progress of the warship and its distance from the gun battery.
The BPR informs the BOP at Fort Newhaven to see if their Directional (optical) Range Finder has a visual fix on the ship to verify the exact range from the guns. In our scenario we conclude that the target is just beyond visual range and the BPR are so informed. Further information is collected from the Radar Station and exact range, course and speed are updated to the BPR. The close defence guns are informed that they are not required and are stood down.
The BPR crew now issue the order to make ready the guns and shells are selected, fused and loaded into each gun along with a full propellant charge. The master gunners are issued with the known target co ordinates and are ordered to engage on command.
The guns are to fire a bracket salvo under the direction of the BPR as of; No.1 gun will fire slightly long in range, No.2 gun will fire as target predicted and No.3 gun will fire slightly short in range. Traverse, inclination, windage and deflection data are now applied to each gun by the master gunners.
All three guns are fired in quick succession while the BOP is instructed to spot the fall of shots where possible. The Radar Station crew now look for any changes in course of the target in response to the engagement. In our scenario we will say that all three shots miss; two fall short while one passes over the warship completely.
At this point the enemy warship will now dictate how the engagement will unfold. If the target ship changes course towards France it will be avoiding further action by increasing the range and the guns will “Stand To”. If the target ship remains steady on its course then the gun battery may well fire another warning bracket salvo at it with the appropriate range corrections made to tighten the bracket and perhaps anticipate that the warship may well fire a salvo in reply from its own heavy calibre main armament.
Lastly, the enemy warship might reduce the range by turning towards the English coast as an aggressive manoeuvre and threaten the coastal battery and port with further bombardment from its main armament; this action would undoubtedly result in both swift Allied Naval and Air Force intervention.
From our scenario it becomes clear that the six inch battery would have been woefully under powered to take on large warships should they be on aggressive manoeuvres against Newhaven Port. They would however have been perfectly capable of destroying smaller vessels such as MTB’s or Submarines should the need arise, far out at sea before the close defence guns would be required to protect the inner Seaford Bay area.
But in reality the construction of this battery was not about actual engagements at all. It was about its deterrent strength and as such it did indeed fore fill its role perfectly in protecting this part of the Sussex coast during the few short months before the war moved on towards its inevitable conclusion.
The superb aerial photograph above shows us what the battery site looked like just after the war in 1949. All three guns can clearly be seen awaiting removal; also evident are the search light locations on the harbour promenade either side of the light railway. In the western moat the power house can be seen that supplied the guns with electricity as can the no.2 power house on the site of the older Lunette Battery near the harbour mouth light house, extreme right. On top of the fort ramparts can be seen the two 6 inch Mk7 guns and to the right of these the two 12 pdr emplacements. Closer examination also reveals the many army buildings that once proliferated the site. (English Heritage Aerial Photo Library)
Friars Bay Radar Direction Finding Station
TQ 4310 0030
This was the main BOP for the gun battery and sited some 2000 yds away high up on the cliff top over looking Friars Bay.
It was self supplied by power and had its own guard room, engine house, transformer house and crew rest area as well as a protective picket fence. The site had centimetric radar, position finder and director equipment and would have been able to locate targets far out to sea before establishing the range and course of a vessel before passing the information on to the battery plotting room.
Nothing of it remains to be seen today except for a few outlines of the picket fence and some building foundations.
TQ 4310 0030
This was the main BOP for the gun battery and sited some 2000 yds away high up on the cliff top over looking Friars Bay.
It was self supplied by power and had its own guard room, engine house, transformer house and crew rest area as well as a protective picket fence. The site had centimetric radar, position finder and director equipment and would have been able to locate targets far out to sea before establishing the range and course of a vessel before passing the information on to the battery plotting room.
Nothing of it remains to be seen today except for a few outlines of the picket fence and some building foundations.
Top Left: The main building shortly before demolition. Top Right: The layout plan of the site. Top: Drawings from the Illustrated London News showing how Radar was used for gunnery ranging during the period that Friars Bay was in use.
3.7in AA Gun Site
TQ 4310 0060
Positioned just above the Radar site was this four gun 3.7 in AA station placed high up on the brow of Rushy Hill. Its job was to protect both the Radar station and the fort gun battery areas as well as offer some protection for Newhaven port from enemy aircraft. It saw a great deal of action during the Luftwaffe’s Baedecker and Steinbock raids of 1942 -1944, the ongoing frequent hit and run raids directed against English towns and finally during the V1 assault in June 1944.
Only a few remnants survive today though the layout can just be discerned from the aerial photograph below. The caravan park built next to it saw many of the original buildings demolished in the 1960's but below are photographs of what remains to be seen today.
TQ 4310 0060
Positioned just above the Radar site was this four gun 3.7 in AA station placed high up on the brow of Rushy Hill. Its job was to protect both the Radar station and the fort gun battery areas as well as offer some protection for Newhaven port from enemy aircraft. It saw a great deal of action during the Luftwaffe’s Baedecker and Steinbock raids of 1942 -1944, the ongoing frequent hit and run raids directed against English towns and finally during the V1 assault in June 1944.
Only a few remnants survive today though the layout can just be discerned from the aerial photograph below. The caravan park built next to it saw many of the original buildings demolished in the 1960's but below are photographs of what remains to be seen today.
After the war when AA Command submitted its performance records to the government a calculation was made based on the number of enemy aircraft brought down and the number of rounds fired to achieve this figure; it was found that each destroyed aircraft had in fact cost some 20,000 rounds to shoot down. This staggering figure was further re enforced by the fact that on one night alone in January 1941 the AA guns protecting London had shot off 28,000 rounds without hitting a single aircraft!
However, it must be said that at the height of the Blitz the very fact that the AA guns could fire back at the German bombers was enough to raise public moral a hundred fold, even though the only damage done was from the shrapnel (and on occasion unexploded AA shells) falling back to earth and landing on roofs and people.
However, it must be said that at the height of the Blitz the very fact that the AA guns could fire back at the German bombers was enough to raise public moral a hundred fold, even though the only damage done was from the shrapnel (and on occasion unexploded AA shells) falling back to earth and landing on roofs and people.
The Battery Site Today
The slide show above illustrates what remains of the battery today and as can be seen it still retains some of its former splendor positioned high up on the cliff edge overlooking the channel. A nice destination for a summers evening walk and to perhaps sit on the gun pit edge and witness the sun setting while remembering the mighty guns that once kept watch here.
GPS Co Ordinates:-
BPR: TQ 4463 0016
No.1 Gun: TQ 4456 0010
No.2 Gun: TQ4464 0008
No.3 Gun: TQ4470 0010
DRF: TQ 4482 0011
With Thanks To:
Newhaven Maritime Museum. NA Files WO192/76 and WO192/220. The War Illustrated. Google Earth. The Illustrated London News Archive.
GPS Co Ordinates:-
BPR: TQ 4463 0016
No.1 Gun: TQ 4456 0010
No.2 Gun: TQ4464 0008
No.3 Gun: TQ4470 0010
DRF: TQ 4482 0011
With Thanks To:
Newhaven Maritime Museum. NA Files WO192/76 and WO192/220. The War Illustrated. Google Earth. The Illustrated London News Archive.
Copyright Steve Sullivan, 2017-2022