Thread: Longues Sur-mer Battery

On my first visit to Normandy I came across four coastal German batteries at a place called longues sur-Mer, situated in the Bay of the Seine, to the North of Bayeux and 6 Kilometres east of the seaside resort of Arromanches, the Longues sur-Mer coastal battery played a vital role in the D-Day landings of 6th June 1944 as its guns pounded the Allied forces.
Also, the battery affords a good insight into how Nazi Germany viewed the coastal defences of the Reich. It is actually just one example of the thirty or so artillery batteries in Lower Normandy during the War and of all kinds of strongpoint’s which grew up in their thousands along the coast from Norway to the Spanish border, the length of what Nazi propaganda referred to as the Atlantic Wall.

The most efficient way to prevent a landing operation on the beaches was to use long range coastal defences to prevent an enemy fleet from approaching the shore. The Longues-sur-Mer coastal battery installations can be divided into three types: the casemates, the control bunker and various secondary defensive works.

Here is a map of the Longues naval coastal artillery battery on June 6th 1944

The Four Casemates are 300 metres inland from the Control Bunker and form a semi circle to maximise the firing arc of their guns to the East and West of the shoreline. Their cliff-top location meant limited visibility down onto the narrow beach at the foot of the cliff. This weakness was offset by directing a 20mm gun at the beach. But what exactly what is a casemate? A casemate is a concrete shelter typically 15m long 10m wide and 6m high, designed to house a gun which fired at enemy targets through an opening, or embrasure, 2.5m in height by 3.85m in length. This gave the gun a firing arc of 120 degrees.

Casemates were guarded by machine gun nests to repel any ground attacks. The small pits created in the concrete were filled with earth and grass to help blend the fortifications in with the surroundings. Hooks can be seen on the bunkers which were used to attach camouflage netting.

Notice the earth piled (bursting layer) up along the sides of the casemates in this picture. This used to absorb the shock of explosions and make the casemates less visible from the air and sea.

Rear entrace into the bunkers

Each of the casemates in the Longues battery was built out of 600 sq metres of concrete and 4 tons of steel reinforcement. To withstand heavy bombing by Allied aircraft, the walls were nearly two metres thick. In addition, to avoid the casemates tipping over during bombing raids the German engineers designed an underground concrete flange which stabilised the bunker by preventing shells and bombs from exploding underneath it. This system of stepped concrete foundations proved particularly effective at Longues when 1000kg bomb exploded, completely ripping away the earth around the casemate but without actually tipping it over. This kind of concrete foundation was used for all naval batteries and worked extremely well. Experts have since corroborated this near invulnerability to aerial bombardment except in the rare event of the protective canopy being hit twice in the same place before the concrete was completely dry. Longues was not affected by the hurried construction in the last months leading up to the invasion building started in September 1943 and the battery was almost complete in June 1944.

In this diagram you can see that the Army casemate had no underground concrete flange which made them Susceptible to tipping over when bombarded.

It was a different story, however at Houlgate, where a 406mm armoured shell fired from a ship anchored 22 km (14 miles) off the coast passed clean thru a casemate. However on closer inspection the third casemate at Longues can seem to have been hit on the right side by a 1000kg bomb which has pierced the canopy. None of the gunners were killed by the falling masonry and in fact it has been proved to have crumbled because of a poor quality concrete mix. Perhaps this was an act of sabotage by a French conscript working for the Todt Organisation.

Longues Battery is the only one in the region to have kept its guns, as you can see in this picture.

These four casemates held German 152mm naval guns dating from 1928 and specially designed for firing on naval targets. If this sounds obvious, funnily enough, not all the coastal batteries were equipped with guns designed for coastal defence. A great many had field guns commandeered by the Germans from the arsenals of armies defeated by the Wehrmacht. Defending the Bay of the Seine were Skoda 210 cannon, French 1916 model 155 guns and Russian 1931 model 122 field cannon. In the words of Swedish artillery Officer B. Stjernfelt, “The Atlantic Wall was armed little by little with guns anything up to fifty years old from 10 different nations with 28 different calibres ranging from 406 to 75mm. Any standardisation was therefore impossible. There was a shortage of spare parts and fittings and sometimes these had to be made. The Longues battery is unique in Normandy in that the guns that fired on the Allied landing forces on the morning of June 6th 1944 are still to be found in situ. Weighing in at around 20 tons, each gun had to be dismantled to get it into the casemate through the gun aperture in two sections first the carriage and then the barrel. The barrel is eight meters long with a diameter of 152mm and had a firing rate of six 45kg shells per minute. The guns range was nearly 20km (13 miles) which put them within striking distance of the future landing beaches of Omaha to the west and Gold to the east. As we shall see, their aim was so accurate that they were to threaten certain Allied ships anchored off the French coast on D-Day. The guns had initially been intended as auxiliary artillery for German warships.

Picture of a casemate at Longues

Despite their ability to resist bombs, the casemates had an Achilles heal their gun aperture. It faced out to sea and was an inviting target for ships whose mission was to destroy the batteries. The casemates had very little frontal protection. Engineers attempted to solve this problem by building what is know as “The Todt front" a concrete protective canopy which jutted out beyond the roof covering and deflected outwards any shrapnel from shells exploding in front of the bunker. Only the naval batteries were equipped with these tiered canopies and along with their rounded shape and the thick bank of earth surrounded them, this set them apart from the Army batteries.

The Todt Front Canopy

The “Bursting Layer" as the earth bank surrounding the casemates was called had the dual role of absorbing the shock of the explosions and making the casemates less conspicuous from the air and the sea. At Longues the gunners were also protected by 10mm of armour plating shielding the 152mm gun room.
The entrance to the casemate was guarded by machine guns which could effectively repel any ground attacks.
Each casemate was made up of a gun room and a pit dug in the ground for storing spent cartridges. Whenever the gun was fired, poisonous gasses was given off and quickly pumped out through an ingenious ventilation system. Inside the bunker, ammunition was kept in two magazines to the rear of the bunker. The ammunition stores for the whole of the battery were located south of the metalled road built by the Germans. This road served as a link between all the different sections of the battery during construction and was subsequently a very useful road leading to the casemates both for the Germans and the Allied bombers who used it as a guide as to where to drop their bombs. This was a surprising oversight on the part of the Germans, who had a particularly efficient method of camouflage; each casemate was covered in asphalt before being partially buried. Even if this task was not completely finished by June 6th, the bunkers were still very difficult to make out. In addition to this, the Germans filled in small pits in the concrete on the outside of the bunker with earth and grass to blend their fortifications in with the natural surroundings. As a final touch, the bunkers were covered with camouflage nets which were attached to hooks that can be seen to this day sticking out of the concrete. These nets were made with strips of material or pieces of sacking. The natural vegetation of the site which was, broom, beach grass and reeds was also used to camouflage the bunkers.

This is a back view of one of the Longues Bunkers where you can clearly see the hooks sticking out at the top.

Although the battery commander, Oberleutnant Zur Zee, settled in the village Chateau and many of those under him were billeted in the local farms and houses commandeered by the Germans, around 10 barracks were built on the site so that, in the event of an attack, the men could live isolated in their camp surrounded by minefields and barbed wire.
Unlike the casemates, these shelters were much less well protected, and some tipped over under bombardment. The shelters were designed for short range defence with machine-gun Tobruks on the roof. Like the control bunker, the conventional right-angled entrance to the barracks was protected by an automatic weapon placed in a loophole which made access even more difficult for enemy troops.

The Loophole would rake the access to the Gun Casemates making it very difficult to gain access intothe bunkers with their right-angled entrance's

During the intensive bombardments in the build up to D-Day, some soldiers preferred to take refuge in the casemates or munitions stores which could endure the bombs much better. To link together all the different elements of the battery, the Germans dug covered communications trenches which provided poor protection during bombing raids. The final defensive elements of the battery on the site in 1944 were 3 anti-aircraft guns located just behind the control bunker, and a mortar Tobruk on the other side of the metal road. The battery was thus a veritable strongpoint equipped to withstand both long and short-range attacks.

The mortar Tobruk used at Longues battery site. Three of The Four bunkers can be seen in the background

The Allied landing forces rightly considered the Longues-sur-Mer battery as an important target to be neutralized as quickly as possible, as it was situated within the American and British landing zones and constituted a threat both to Omaha Beach to the west and Gold Beach to the east. Moreover, the seaside resort of Arromanches, where the British Mulberry B artificial harbour was to be assembled, was also within the range of the Longues guns. For all these reasons the Allied bombing raids during the build-up to D-Day were of vital importance.

Inaccurate aerial bombing explains the scattered bomb craters.

His visit to Longues on May 9th 1944 appears to suggest that the Longues battery also loomed large in the mind of Field-Marshal Rommel. Like the rest, the coastal battery at Longues was repeatedly bombed by the Allies in systematic raids from April 10th 1944 on. These raids were carried out along the length of the coast from Brittany to Ostend but the bombers concentrated more particularly on the future landing zones.

Invader A 26 Bomber

The attacks that took place on May 28th and June 3rd 1944 were particularly trying for the Longues gun crews - a German report stated that they received over 1500 tons of bombs. Although the concrete case mates withstood this pounding, not so the communication lines linking the casemates to the control bunker. Altogether, twenty raids on the coastal batteries in Normandy caused forty deaths, 73 injured and 10 missing according to a report from the German Admiral in charge of the Channel coasts.

Hudson Bomber

The morale of the troops in the bunkers, however, reached a new low during the night preceding the Allied landings when around 100 bombers dropped over 600 tons of bombs on the battery. Unfortunately, most of the bombs hit the nearby village of Longues, which was razed, killing five civilians. This pressure on the battery did not let up as, at daybreak, a further wave of light and medium U.S. Airforce bombers came to finish off the Longues battery and other coastal batteries within the landing zone.
Despite the absence of German fighters, the bombing raids over Longues and elsewhere were only partially successful owing to the thick layer of cloud which lay over Normandy throughout June 1944. Although communications were cut and the landscape around Longues rather resembled a moonscape, the four guns remained intact and able to fire against enemy ships. Aware of such a possibility, the Allies had planned a naval bombardment, during the half hour before the troops were due to land on the beaches.

Marauder B26 Aircraft

Cruisers, battleships, and destroyers dropped anchor opposite their targets. To help them hit their targets, a few vassals were equipped with radar, and adjusted their fire to co-ordinates provided by spotter planes endlessly circling over the coastal batteries to correct the fire of the warships lying of the coast.

After the soldiers defending the battery surrendered, the British troops occupied a site 400 metres further along the coast to build one of twenty temporary airfields, the B 11, which was operational between June 26th and September 4th 1944.

Pictures 1, 2, and 3 Show Preperation and Construction of the Temporary British Airfield.

This A.L.G. (Advanced Landing Ground) could house no less than 54 planes and its runway was I200 metres long by 50 metres wide. The squadrons landing here were generally allocated to 3 different airfields, choosing where to land as required by congestion, dust and weather conditions. The runway at Longues was made of a square steel mesh fixed to the ground with special pegs. The Longues airfield took one week to construct.

To cover the runway, the British set up anti-aircraft guns on the roof of this bunker and stored ammunition inside, However, there was an accident which brought about the explosion of this makeshift magazine and caused the deaths of four soldiers. The violence of this explosion explains the total destruction of the blockhouse built by the Germans and the twisted gun barrel in front of the casemate.

Extracts taken from Pierre Clostermann Interviews to several Newspapers.

Pierre Clostermann, Le Grand Cirque.
Presses de la Cite, 1948:

The building of A.L.G.s in our sector was considerably delayed by unexpected German resistance in Caen, which, according to the plan, should have been taken on the afternoon of D-Day. As it turned out, the three first landing strips to be constructed almost came under fire from heavy Flak 88mm artillery batteries. Our planned Advanced Landing Ground at Bazenville where we had landed four days earlier had to be abandoned. Finally, it was settled that B II at Longues would be our airfield.

Pierre Clostermann, Une sacree guerre,
Flammarion. 1990:

And the chaos continued. The City of Glasgow journal reported that I had shot down a German plane at one end of our airfield at Longues and another one at the other end. All this is slightly exaggerated. I did shoot down a Messerschmitt 109 at one end of the runway, but the pilot from the other plane baled out much further away.

On D+ 5, a team of British engineers arrived to lay and camouflage, west of the Longues battery, under-water telephone cables and the mobile equipment needed to ensure communications with the Allied HQ in Normandy and SHAEF headquarters in England. This photograph shows two British engineers, Cotes and Walford, sat posing on casemate #2 Gun.

Today, although the craters have been filled in and the mines have been removed, the vegetation has grown back and the visitor to Longues can fully enjoy the view, the presence of the enormous case mates and the control bunker, the metalled road under the tarmac and the roofs of the magazines and shelters emerging from the earth are there to remind us that this is a true place of remembrance of the Second World War.

Taken from the road besides the Control Bunker looking down towards Arromanches where you can see the Mulberry harbour clearly from this picture.




This is the View looking left from standing on the Control Bunker