Defnses of the Seine River

[charwo]

In the invasion of Normandy, little talk is given of why the Allies chose the western side of Normandy and not the eastern side, namely Rouen. I've been playing custom scenarios for a very old game, Civ 2, which is still active, and I've found the best way to land in Normandy is to ignore the beaches altogether, by using frogmen to demine the mouth of the Seine, suppress the 255mm batteries in Le Harve, use airborne troops and commandos to seize the city while the cruisers and such sail into the tidal estuary shelling everything that moves and deploying heavy flamethrower tanks and heavy artillery to the city and moving them rapidly north to hit the 255mm batteries from behind and seize LeHarve, opening up the Seine. And because there are no beaches, there's little armor, and the armor in Normandy is stuck between Caen and Cherbourg, and the rail system is so screwed up AND there's virtually no Luftwaffe fighter presence in France, so it's very easy to interdict the roads east and west of Rouen, and it still isn't anywhere close to Calais, so Hitler will still think this is a diversion.

Now in the game, I was able to sail a cruiser down the Seine with units of 155mm shells and was able to seize western Paris in the first week, using very fast motorized troops and M5 Stuarts That almost certainly is not realistic, even if you had a shallow draft vessel with 155mm guns, which actually sounds fairly doable. But given the nature of the surprise and gen the scenario author's reputation for historical accuracy in unit placements, I'm tentatively inclined to believe that there were no troops and no defenses to speak of between Rouen and Paris as of early June.

I'm wondering if I'm onto something. Politicians and generals, who are required to be politicians usually don't take chances, especially with capital ships, and doing this is more or less the Dardenelles run the Admirals wouldn't let Churchill do in Gallipoli, but you also have a hell of a lot of airpower and more battleships to duke it out with the shore defenses, with radar targeting to boot.

So, even if this idea is absurd, what were the defenses like on the Seine River in 1944? And what were the dispositions further east towards Calais should Hitler call the bluff and send them westward? And do they have enough gas to get there considering the interdiction of the railroads and the critical gas shortages after 1942?

[Carl Schwamberger]

What was your initial supply discharge? How many tons daily or weekly during the opening weeks? How did that limit or aid the build up of combat forces?

... what were the defenses like on the Seine River in 1944? And what were the dispositions further east towards Calais should Hitler call the bluff and send them westward? ...

The defenses there were relatively strong. The old French fortress system around LeHavre covered a considerable area. As at the other ports it had been reinforced after the occupation, and that had been in progress from 1942, long before the beach defenses between the ports were well developed. On the map the area along the Seine estuary and the adjacent coast looking northwest appears well developed. Note that the heavy artillery Near LeHavre was able to attack the eastern most Allied beach next to Caen, and interfere with supply discharge across that beach.

The commander of the 15th Army had control of his local reserves, which in the context of a defense were not trivial. & the motorized portion had fuel on hand for at least several days operations. The reserves connected to Hitlers approval were the Panzer group located in the Paris region, and Hitlers final approval in shifting units from on army to another. I'd have to check the maps, but his location is near the boundary between the 7th and 15th Armies, which gives both army commanders and Rommel as AG commander some control over initial concentration of reserves.

There also seems to be a misunderstanding in the English language analysis of the German view of where the invasion would come. Yes LeHavre is in Normandy by traditional French view. However the Germans were thinking in terms of east of the Seine river, or west of the Seine. This is one reason why they placed the boundary of the 7th & 15th Armies where they did. So one army would be responsible for a sector the Germans though of as a single are in terms of military geography. In the German docs or opinions I've read the name 'Normandy' is not used regularly. Names like Cotientin, Calvados, Calais, Bulogoune, or a army or corps designation are used as often or more often that Normandy. Bottom line here is LeHavre was considered part of the area of primary threat. The Calais sector in the popular lexicon. Given that Hitler was persuaded OTL that the landings on the Calvados were a diversion & the primary attack would be east of the Seine its likely the reserves, from all sources, would be released sooner for counter attacks.

There are a few decent books in English on the German views. I'd like to hear opinions on what the best on this subject might be. Thanks.

[charwo]

Well, in the map, it's on a 9 square pattern where every square is nine miles, and every unit is about regiment strength. Logistics don't exist per se in Civilization 2, although in practice on the offensive logistics are simulated by movement capacity. There are 10 landing craft units that can hold 2 land units, which given there were 1,500 non-control landing craft of various sizes that's ten landing craft so the numbers add up. The landing craft have a movement of 18, and most units have a movement of 2, and land units on a road can move four squares on a movement point meaning you can gun it for eight squares or about 70 miles in a week.

Now all of this hinges on the fact that airplanes can interdict road (which is both roads and rail in this scenario) by sitting on top of them, which is historical, there's a road connection east of Rouen almost on the coast which connects Rouen and Le Harve to Amiens and Boulogne. this crossing is critical as there's a buttload of tanks and Panzer Grenadier regiments just to the east of this crossing and in Amiens. Interdict this road, they need to go off-road, which means they cannot reach Rouen in the first week. And obviously given the size of the Seine tidal pool, the panzers in Normandy cannot reach Rouen either IF you interdict the river crossing southeast of Rouen.

What I'm going to call the Rouen-Dieppe can also be interdicted by the road just south of Dieppe, which is also a crossroads, which is defended with a "blockhouse" heavy fortifications you need heavy artillery (5.5) and/or engineering units to clear out. and they are supported by Panzer IV and Grenadiers, and Rouen is as you say heavily fortified with 88s, artillery, and another two regiment PanzerIV and Grenadier combo.

This is how you break them:
1. Frogmendisable the mines in the hours before the operation, on the quiet. It took me three recon teams, which can scout and sabotage lone units and a Battleship for the coup de grace, but I imagine the RN has better, more expandable craft for the final cleaning. This is a turn-based game so the Germans can't fire the 255mm battery reflexively, and I think if you properly suppress the fortification with battleships and airpower you can keep their eye off the ball.

2. GIven we have total air supremacy over northern France I land four Regiments of Paras in the forests north of Rouen with the goal of taking out or weakening of the AA units. I love paras, but they are expendable, landings are also made behind LeHrave to confuse the enemy and allow a bypass corridor. Speed is of the essence though.

Here is an ahistoric fact: due to game mechanics, AA units also have a +100% defense to missile units, which in this scenario include heavy artillery, which means the AA units are as good as tanking artillery fire as Air attacks. In reality, I'd just sent the cruisers in start blasting AA positions with naval artillery first using Para elements as spotters, then murder them to death with tactical bombers and let the Paras come in and mop up.

3. Once Rouen is taken, two landing units of 30 craft carry one 5.5 artillery and three engineering units, one IDed as a Churchill AVRE though the unit picture is a Crocodile spewing flames, two American counterparts IDed as POA-CWS, which I had a hell of a time Googling as Sherman Flamethrowers, and land them in Rouen so they have full movement capacity.

4. the 5.5 covers the flame tanks and they take out the blockhouse, then the 5.5 inch knocks out the tanks, although in retrospect, maybe I shoulda used a 17 pounder AT gun instead. As it is, I skirt the range of the artillery emplacements in Dieppe and hit the 225mm battery with the AVRE and the second POA until everything is dead. Then I use Le Harve as a secondary staging area. Now because I didn't choose stating placements I couldn't deploy all six regiments of Flamethrower tanks or I would have taken Dieppe too.

5. Funny thing, the armor in the Paris region isn't in Paris and cannot reach Paris in the first week, not in a Condition to fight anyway and that's good for me because there's a Tiger Regiment in Reims and a Pather regiment in Sedan. So I sail a cruiser with 155mm shells up the Seine and shell the hell out of the garrison of West Paris after running up a combo of American motorized infantry and an M12, the M12 being used to silence the Flak 88. This unit's goal is to raid, sever communications and die gallantly and they do get chewed up by the few Luftwaffe bombers in the area.

The Blockhouses in Caen are all homed, which is logistically supported by Western Paris, and you take Paris, they disappear. I think this makes sense as taking Western Paris is going to panic a lot of the Normandy defenders because they don't really have the means to leave other than foot.

6. In the next week (Overlord +6 or so), as the Panzers move towards Rouen, using recon teams to sabotage and ambush the units, I use airpower to turn the region east of Rouen into the Highway of Death, minus the highway. Airpower again interdicts counter as the Paras not used to take LeHarve are used as mobile reserves to take Amiens and eastern Paris as mobile artillery comes in clear out what the airpower couldn't.

Here's where things might or not break down. The mobile Normandy units don't move east, they move West to port the port of Cherbourg, Avranches, and St. Malo, hoping to use the Bodcages to make a tenacious defense. Thing is I'm profoundly uninterested in Armor, the armor doesn't scare me, not even the Tigers. well mostly. I'm scared of the Blockhouses, armor is to bypassed when possible and when necessary to be logistically hit by recon teams and only as a last resort, to be destroyed from the air.

Except for the V-1 Bombs Amiens would have been the front line for a long time, but as it is, taking Lille is a top priority. Other than that, I begin cutting off Normandy with the taking of Le Mans, taking Caen is a formality as this point because the Wehrmacht has left fortifications and the Hiwis are deserting like mad, so no Saving Private Ryan as we understand it. Airborn troops used like Transport Verbund, with air units hammering static infantry as the airborne leapfrogs from town to town.

Until I get to the Siegfried Line there's virtually no resistance. As long as I scout the cities properly and know where to bring the combat engineers for Blockhouses fast and easy. Clearing out the area between Caen and St. Malo is tricky. But y the end of July I've liberated all of northern France except St. Nazare. and Dunkerque and all of Belgium but the coast south of the Schelde.

But given the devastating effects of oil shortages, airpower and Bagration, the absence of German response seems to make total sense

[Aber]

In the invasion of Normandy, little talk is given of why the Allies chose the western side of Normandy and not the eastern side, namely Rouen. I've been playing custom scenarios for a very old game, Civ 2, which is still active, and I've found the best way to land in Normandy is to ignore the beaches altogether, by using frogmen to demine the mouth of the Seine, suppress the 255mm batteries in Le Harve, use airborne troops and commandos to seize the city while the cruisers and such sail into the tidal estuary shelling everything that moves and deploying heavy flamethrower tanks and heavy artillery to the city and moving them rapidly north to hit the 255mm batteries from behind and seize LeHarve, opening up the Seine.

Naval batteries map

http://www.amis-du-suffolk-rgt.com/index.php/en/bunkers

Operation Astonia

https://www.ibiblio.org/hyperwar/UN/Can ... ry-14.html


In reality you need to take Le Havre from landside which needs at least 2 divisions; plus a lot more facing eastward to stop German reserves from interfering. You need to first land them and their supplies before attacking Le Havre, remembering that the Germans have torpedo boats in Le Havre itself.

[Carl Schwamberger]

...
In reality you need to take Le Havre from landslide ...

Standard procedure since the Romans, maybe even the Sumerians. Its a rare day a fortified & defended port is taken directly from the sea. When it happens the defense was flawed, and the attack force made few mistakes. The attack on Dieppe was against 3000+ years of accumulated military experience. Take fortified ports from the rear.

[Carl Schwamberger]

Well, in the map, it's on a 9 square pattern where every square is nine miles, and every unit is about regiment strength. Logistics don't exist per se in Civilization 2, although in practice on the offensive logistics are simulated by movement capacity. ...

Looking at the record LeHavre had a nominal peace time capacity of five or six thousand tons intake daily. At the allowance of 900 tons daily per division slice thats six and a half or maybe seven divisions plus corps & army support, and a large tactical air wing ashore. The actuality was It took much of September to restore LeHavre to operational status. In October its intake totaled 61,731 tons, or 2075 tons daily. Almost enough for a reinforced corps. In November the intake more than doubled to 148,654 tons, or 4,955 tons daily. About five and a half divisions & supporting units worth of supply.

Cherbourg had a nominal peacetime average of 10,000 to 12,000 tons daily & its wartime intake was boosted to a average of 15,000 tons in August and 20,000+ in September.

In the invasion of Normandy, little talk is given of why the Allies chose the western side of Normandy ...

Several different staff groups had chosen the Calvados & Cotietin coast over every other site during 1942, 1943, and 1944. There was a actual invasion plan worked out in the summer/autum of 1942. that plan targeted the beach adjacent to the village of Madaliene, the south end of the are Labeled UTAH beach 18 months later. The reasons were numerous & included:

1. Proximity to the rear of the port of Cherbourg.

2. Sheltered from Atlantic storms by the Cotintien peninsula

3. Forces available in 1942 could shut off the peninsula.

4. Several local airfields the Germans had maintained

5. Solid broad beach to support landing of following on forces and supplies.

A year later COSSAC revisited the question & considered all sites from the Dutch coast to the Spanish border. Morgans staff recommended to Marshal and Alan-Brooke the Calvados coast (directly adjacent to the previous selection) for similar reasons. Solid gravel beaches, proximity to Cherbourg, airfields that could be swiftly captured, protected from the western storms.

Five months later Montgomery & Eisenhower separately reviewed the options and kept the COSSAC selection. Identifying the same reasons & other advantages.

Eight to ten years earlier in the mid 1930s a class at the US Army Staff and Command school were given the problem of selecting a site for invading a hostile Europe. Their recommendations included securing the UK as a forward base, and using Normandy as the primary invasion site & a early capture of Cherbourg. I could go on here, but we see that groups of both US and British Army leaders and their staffs separately and repeatedly selected western Normandy over all other possibilities.

[Aber]

Looking at the record LeHavre had a nominal peace time capacity of five or six thousand tons intake daily. At the allowance of 900 tons daily per division slice thats six and a half or maybe seven divisions plus corps & army support, and a large tactical air wing ashore.

The standing joke from COSSAC planners - "you'd need more than 7 divisions to take it".

[JKernwerk]

Charwo,
Do not think they forgot in the original planning.
I my oppinion some of the con's were;
Le Havre is surrounded by high cliffs and canals, only landing in the harbour it self and landing at a river mouth is hard to do because of watercurrents.
The same goes for most of the Seinevalley and the parts that are flat it is wet polders, really bad tankcountry.
When you land on the south side of the Seine at the same time you can not meet in te middle because of the river (so not one front), also the coast is mostly hard to cover for tanks (a bit like Omaha beach but mostly worse).
And if you land in two corners it is harder for you to deploy and keep moving in the initial stages.
The canal Riva-Bella-Caen worked pretty well as a natural border to keep the 21st Panzer at bay that could also hepled the Allies when landing South of the Seine.
255mm batteries were not present (did not exist in the German Army), but Le Havre was heavily armed with Flak and all sorts of coastal and divisional batteries up to 38cm (battery was not ready but i assume one gun could fire), on the South there were more coastalbatteries then in the actual landingplaces.
I also do think that te broad river was likely to waste more para's then the innondations did at Utah also when they had to land a bit more south (lets say between Pont l'Eveque and villerville) there were much more forests than at Utah and the British landinggrounds so harder to land if we assume a wide spread landing in the night and more losses due to the trees.
JK

[Carl Schwamberger]

... 255mm batteries were not present (did not exist in the German Army), but Le Havre was heavily armed with Flak and all sorts of coastal and divisional batteries up to 38cm (battery was not ready but i assume one gun could fire), on the South there were more coastalbatteries then in the actual landing places ...

Heavy cannon west of LeHavre did fire on the eastern most beach near Caen. After a few weeks supply transit across that beach was ceased as the battery could not be reliably suppressed and unacceptable losses in ships/landing craft were threatened.

[JKernwerk]

That must have been battery Houlgate the only German coastal battery that could fire on that beach (The sister battery at Mont canisy was already to far away) if we look at the range. but that one was bombed and shot at by heavy ship guns. I do not think it could shoot directly on the beach with all guns only two bunkers were ready and these guns had limited traverse that leaves 4 guns that could fire 360 degrees. Today the whole hill where the battery is located is cratered by the bombing and shelling and the casemates for the 155mm were hit hard and we assume the guns knocked out. The guns of Merville were all knocked out by the British para's before d-day but it could be there were more divisional batteries like Merville that could just hit the beaches at Riva Bella.
JK

[Carl Schwamberger]

I recall it was the threat to cargo ships off the beach that caused reduction or cessation of operations there. Don't know if any projectiles actually hit the beach area in use.

[Manuferey]

Plans to land Allied troops in Le Havre were indeed considered in 1942-1943 under Operation RANKIN as contingencies in case of a sudden change in Germany’s military strength and determination to continue the war (like the revolution in Germany at the end of 1918).

That must have been battery Houlgate the only German coastal battery that could fire on that beach (The sister battery at Mont canisy was already to far away) if we look at the range.
JK

"On the Eastern static flank, an enemy battery east of the River Orne and another at Le Havre made it necessary to discontinue unloading on Sword Beach.”
Source: DEPARTMENT OF THE NAVY -- NAVAL HISTORICAL CENTER
OPERATION NEPTUNE - CHAPTER VIII - BOMBARDMENT AND OTHER DEFENSIVE OPERATIONS AGAINST ENEMY LAND FORCES

The battery near Le Havre was 3./HKAA 1254 at Le Clos des Ronces with its 17 cm K18 guns.

Emmanuel

[Carl Schwamberger]

The description of the three RANKIN operations I seen indicated they were designed for seizing ports from a severely degraded defense. Either where the garrisons were reduced through withdrawals, demoralized & ready to flee or surrender, or both. The descriptions had these ops executed by Airborne and Commandos. with ordinary infantry divisions following through secure beaches or the port. One such description is on the HyperWar web site. If anyone is able to post more complete information it would be useful.

[JKernwerk]

Emmannuel,
How is it possible they concluded that a battery of K18's at Le Havre could fire at Sword beach.
The max. range was 28km that would be about Cabourg, to give fire at Sword beach they would need another 10km or more (Riva Bella was about 37km away).
Did they expect newer ammo that could fire further?
JK

[Carl Schwamberger]

This: https://www.themaparchive.com/product/t ... june-1944/

...site shows the location, identification, and range of the coastal artillery batteries for 6 June. It shows most of the the cannon west of Le Havre could not range SWORD beach, but their range does interdict the roadstead off shore where the cargo ships would transit and anchor for offloading on SWORD Beach. It does show one battery that could reach all of SWORD Beach & the Edge of JUNO Beach. This matches the accounts I have read, that the primary threat was to the ships & was the rational for halting discharge across SWORD Beach. I'd also note there are a couple other batteries shown east of Ouistriam that could interdict the beach as well.