D-Day Questions

July 29, 2005 6:36 AM

I watched The Longest Day last night and had a few dumb D-Day questions afterward: 1) Why wasn't German U-Boat activity in the North Atlantic considered a major impedance to the invasion, 2) Why didn't German radars pick up the tremendous column of men & machines heading toward France, 3) Why wasn't more air cover sent in far ahead of the armada to take out the huge gun emplacements on the beach first, and 4) in order to risk less casualties once they hit the beaches, why didn't the Allies roll out tanks & armored vehicles first instead of releasing waves of vulnerable human targets from their LCVs, many of whom were killed immediately?
posted by dhoyt to grab bag (32 comments total)

On (1), I believe U-Boats avoided the English Channel (lots of Allied minefields), and also the U-Boat fleet had pretty much been hammered by that point (743 boats lost by the end of the war according to Wikipedia, 751 according to the linked site), due in no small part to Enigma along with improved technology (depth charges, sonar, radar).

I'm not an expert, though. I'd be interested in the answers to (3) and (4).
posted by Leon at 6:55 AM on July 29, 2005

Addendum.
posted by Leon at 6:59 AM on July 29, 2005

I think the U-Boat threat had been by and large dealt withby 1944, or at least it was not the threat it had been during the first half of the war, and as for the radar I'm not sure the Germans had radar that powerful or sophisticated at that stage to pick up movements of this kind. I think it was more for picking up planes rather than ground or sea movement.

As for the tanks, they did launch tanks with the first wave of foot soldiers but I think there were problems with them sinking and I don't think many of them got to the beach. Basically, you need something a lot more solid than a boat to put large quantities of armour ashore.
posted by jontyjago at 7:01 AM on July 29, 2005

As for 3), there had been a huge air and sea bombardment before the invasion. But if emplacements are dug in well enough, you can bombard the shit out of them and they can still survive. And, adding to that, some of the bombardment strength was diverted to maintain the pretense that the invasion was going to happen at the Pas de Calais (not sure if this diversion really affected the intensity of the Normandy bombardment, but it's at least plausible).

4) Landing a tank amphibiously is a tough thing to do. As jontyjago said, there was some effort to land them, but it's just easier to throw a whole lot of people onto the beach and then unload tanks when you've got control.
posted by COBRA! at 7:09 AM on July 29, 2005

OK, first here is a good timeline, and PBS has an excellent docu about D-Day, and here is a good overall map.

The Allies did roll out tanks and stuff, but they had to build the Mulberry Harbors (good History Channel program) which were giant concrete boxes which were sunk for breakwaters, and a giant pontoon bridge so that deep water ships could unload. But they had to take the beach head first, and that took men. And many of the landing beaches had obstacles which needed to be cleared for heavier mechanized vehicles.
posted by plemeljr at 7:11 AM on July 29, 2005

1) The Allied campaign against U-Boat activity, otherwise known as The Battle of the Atlantic had already been decisively settled a year earlier. By the time of the D-Day invasion, German U-Boats were being whack-a-moled by anti-submarine aircraft in the Bay of Biscay and the main French sub bases at Lorient and St. Nazaire were being regularly pounded by 1942.

2) German radar actually did pickup the fleet, but Hitler believed that the Normandy landings were a feint, and that the real attack would occur at Calais, and had kept his main panzer divisions back from the beaches.

3) Bombing technology, especially against hardened gun emplacements was much less accurate than it is today. Keep in mind that the allies had little in the way of nightvision equipment or guidance mechanisms, making night-time raids against flak protected, fortified targets an exercise in operational futility. There were bombing raids conducted against shore defenses, but in large part, these attacks landed well inland, and had little effect on the defenders. The thrust of the main air operation was to severe communication and transportation infrastructure and prevent the beach defenders from being reinforced.

4) The beaches were strewn with anti-tank obstacles and mines that had to be cleared by infantry before tanks could make their way up the beaches. Besides, choppy Atlantic waters made it difficult to land and operate an amphibious tank under hostile fire. The most significant use of tanks during D-Day, involved an array of vehicles with jury-rigged modifications (ie. fitting a massive set of rotating flails in front of a tank to trigger mines) specifically adapted towards beach landings against static hard targets (none of these designs would've fared well against another, mobile tank foe; but as far as being pimped out for getting troops through a beach defended by bunkers they were quite excellent) and they were only used on Gold Beach, which had much calmer weather than Omaha or Juno.
posted by bl1nk at 7:24 AM on July 29, 2005

Oh, and all manner of amphibious vehicles were used - LCM (3) could land a mechanized vehicle right on the beach - but they were slow, and at Omaha beach, underwater obstructions prevented many ships from landing. The first wave was concerned with getting as much men on the beach as possible to take the beach head before getting pushed back to the sea like at Dunkirk.

Here's a good naval overview which is interesting.

And as for air power, the main difficulty was that all of the emplacements were heavily fortified and protected, leaving a ground assault as the only choice. The Navy also began pounding down positions once in range, but remember the accuracy wasn't the best. (or what bl1nk said)
posted by plemeljr at 7:27 AM on July 29, 2005

• Because they couldn't get to the Allied ships:

  By 1944, advances in radar and air cover effectively prevented the U-Boats from even nearing the fleet, and along with an exhausted and demoralized German Navy submarine officer corps, removed any threat the U-Boats may have posed.

  They were also running out of U-boats.
• Maybe because the Allies dropped aluminum foil to trick German radar into thinking the invasion was happening somewhere else. This was one of the tricks the Allies used to misdirect the Germans. (The "tricks" link was written by someone after watching The Longest Day.
• They did bomb and shell the gun emplacements, but they didn't want to do it too far in advance of the invasion because that would have revealed the location, and the emplacements were well constructed (fuhgettaboudit, they're Germans).
• They tried amphibious tanks but most of them sank. At Utah Beach, three out of four LCCs (Landing Craft, Control) sank, so they couldn't direct the LCTs (Landing Craft, Tank). At Omaha Beach, the current caused everyone to land in the wrong place (see also Saving Private Ryan). And the obstacles caused problems.

posted by kirkaracha at 7:31 AM on July 29, 2005

They didn't have enough tanks. Armored vehicles are vulnerable to antitank rockets without an infantry screen. Engineers and infantry were landed first to reduce the obstacles and let the tanks break through. That was the idea, anyway.

Another question might be, why didn't they land at night?
posted by atchafalaya at 7:57 AM on July 29, 2005

why didn't they land at night?

IIRC, the fortifications had searchlights, so if they'd landed at night the invaders would have been **singing** blinded by the lights, shot up by the Germans in the wee hours of the night.
posted by ROU_Xenophobe at 8:54 AM on July 29, 2005

re: night attack, I also believe the main factor was waiting for the right tide conditions. Too high and the landing craft would have been stuck on the obstacles the Germans placed on the shoreline, too low and the landing craft were in danger of coming ashore too far from the beach, exposing the soldiers to even more hazard.
posted by plemeljr at 9:03 AM on July 29, 2005

plemeljr - don't you mean Dieppe? Dunkirk wasn't an amphibious landing operation at all. More like a reverse of one.

as a further aside, the new D-Day Museum in New Orleans is a little heavy on the "Greatest Generation"/Stephen Ambrose flavor of overly sentimental World War II scholarship, but it does a pretty comprehensive job of covering, not just the Normandy landings, but also similar amphibious operations that occurred in the island hopping operations of the Pacific theatre. It's worth visiting if you're in the area and are a military hobbyist.

atchafalaya - night landings are fine for infiltration and raiding operations, less so for massive invasions. It's more difficult to see landmarks and uniforms at night, increasing the likelihood of disorientation, friendly fire, and unit isolation. Timing it for dawn gives you some of the surprise element of a night attack, but without all of the disadvantages of poor illumination.
posted by bl1nk at 9:10 AM on July 29, 2005

2) German radar actually did pickup the fleet, but Hitler believed that the Normandy landings were a feint, and that the real attack would occur at Calais, and had kept his main panzer divisions back from the beaches.

This was by Allied design. We knew they were on to us in terms of code breaking, etc., but that they didn't know we knew. So a lot of false radio traffic was set up indicating the main thrust would come at Calais (the closest point to England, so a very logical point of attack). The Nazis bought it hook, line & sinker. (There were even false troop emplacements set up near Dover to reinforce the idea via German aerial reconnaissance
posted by Doohickie at 10:00 AM on July 29, 2005

IIRC, it got even trickier than that. There were German agents that we had turned or caught. And the Germans knew that they'd been turned. And we knew the Germans knew that they'd been turned. But the Germans didn't know that we knew that they knew that we'd turned the agents. So they fed the agents true information that the invasion would happen in Normandy, and, as predicted, the Germans took that as intentional misinformation (since they knew that the agents had been turned) and concluded that it was even more likely that the invasion would be at Calais.

Something like that. Lordy, information games are fun in real life.
posted by ROU_Xenophobe at 10:43 AM on July 29, 2005

I remember something from history class about the air support coming too late to be really helpful. Clouds, or diversions, or they couldn't get as much as they want... something like that.
posted by devilsbrigade at 11:24 AM on July 29, 2005

Vizzini: You only think I guessed wrong! That's what's so funny! I switched glasses when your back was turned! Ha ha! You fool! You fell victim to one of the classic blunders! The most famous is never get involved in a land war in Asia, but only slightly less well-known is this: never go in against a Sicilian when death is on the line!! Ha ha ha ha ha ha ha!! Ha ha ha ha ha ha ha!! Ha ha ha... [Vizzini stops suddenly, and drops dead to the right]
posted by bl1nk at 11:29 AM on July 29, 2005

Wow. So many excellent answers. Thanks guys. This is definitely a thread worth bookmarking.
posted by dhoyt at 11:34 AM on July 29, 2005

1) Why wasn't German U-Boat activity in the North Atlantic considered a major impedance to the invasion

Well, a) it was -- it made it so difficult to get men and materiel to Britain that the invasion was delayed for years (some Commonwealth troops were brought over in 1940, and their first combat was D-Day); b) the Allies pretty much owned the Channel, as stated; c) the U-boat was an open-water hit-and-run offensive platform -- it stayed away from shore deliberately, and watch Das Boot for the terror of slipping through Gibraltar; d) shore batteries and air defense by Germany were not negligible threats.

Most of the other points are well answered.

One of the biggest things on our side was the dissension in German ranks regarding the invasion. They knew it would happen, the only question was when and where. Invasion activities that alerted command staff began as early as midnight, and even so it took nearly a day for Berlin to allow redeployment of armor to counter the threat. In that context, having radar warning (which I'm not sure they didn't have, at some level) wouldn't have been very useful.

One of the big what-ifs of history. What if Hitler hadn't been so bugfuck crazy by then that he kept his smartest generals -- including Rommel -- from doing what they needed to do? We were very lucky.
posted by dhartung at 11:50 AM on July 29, 2005

Operation Fortitude: We put Patton, the most famous American general, in command of the fake First U.S. Army Group (FUSAG), which was equipped with rubber tanks, plywood cannons, and canvas ships. (Ken Follett's Eye of the Needle is a suspenseful book and movie about a German spy who discovers that FUSAG is fake.)

FUSAG was based in southeast England and intended to trick the Germans into thinking the invasion would be at Calais, which was a more likely invasion site because the English Channel is narrower there, it's closer to Germany, and a landing there wouldn't have involved crossing major rivers (the Seine and the Somme) on the way to Germany.

The plan worked:

powerful German combat forces, capable of smashing an invasion, were fixed out of place for several weeks. German forces north of the Seine, away from the actual landing sites, were actually stronger in July than they had been on D-Day, one month prior. Movements of any significance did not occur until after the Allied breakout from their beachhead, when the Battle of Normandy was already lost for the Germans.

Rommel wanted to position the panzers close to the beaches so they could counterattack immediately, but he was overruled and the tanks were positioned in a more central location away from the coast.

The BBC has a good article on an archaeological survey that explained what happened to the amphibious tanks.

Encyclopædia Britannica's Guide to Normandy 1944 has tons of D-Day related videos and some excellent charts and diagrams.
posted by kirkaracha at 1:15 PM on July 29, 2005

Rommel wanted to position the panzers close to the beaches so they could counterattack immediately, but he was overruled and the tanks were positioned in a more central location away from the coast.

The German's bypassing of the Maginot Line (in which, I believe, Rommel effectively lead the way) seems to indicate that this sort of defense is generally unsuccessful against a mobile, armored foe. Why did Rommel think it would work in this case?
posted by event at 1:28 PM on July 29, 2005

bl1nk: did you mean Dunkirk or Dieppe - Actually, both. If I recall from Churchill's memoirs (a must read if you can stomach 5 volumes), that the British were still haunted by the evacuation of Dunkirk and were not about to be driven into the sea once again.
posted by plemeljr at 2:15 PM on July 29, 2005

The German's bypassing of the Maginot Line (in which, I believe, Rommel effectively lead the way) seems to indicate that this sort of defense is generally unsuccessful against a mobile, armored foe. Why did Rommel think it would work in this case?

Rommel didn't want to line the panzers up in a bunch of static Maginot-style formations. He wanted to have a mobile striking force near the beaches. Huge difference.
posted by COBRA! at 2:20 PM on July 29, 2005

Doesn't that still boil down to spreading your armor out into a thin shell?
posted by event at 2:25 PM on July 29, 2005

No. You mass your armor at some central point behind the beach where it can strike reasonably quickly with a lot of force. That's the whole point, that you're concentrating it where you think you'll need it. The thing is, you're rolling the dice then that the beach you want to protect is the correct one. Hitler had swallowed the Calais deception so thoroughly that he insisted the armor be kept in reserve at a central point way further back, and wouldn't release it for hours after the invasion had started.
posted by COBRA! at 2:42 PM on July 29, 2005

The 21st Panzer Division (which had been part of the Afrika Korps), was close enough to counter-attack, and part of the division reached the coast between Sword and Juno, but they didn't have enough reinforcements.

Hitler was asleep during the invasion, and they didn't wake him up for hours. They couldn't move two panzer divisions without his authorization; by the time he released them, it was too late. (And Rommel was in Germany visiting his wife.)

p.s. "COBRA!" is a very exciting username.
posted by kirkaracha at 4:26 PM on July 29, 2005

The German's bypassing of the Maginot Line (in which, I believe, Rommel effectively lead the way)...

As much Guderian if not more, surely?
posted by IndigoJones at 6:31 PM on July 29, 2005

Guderian, sure, but:

In 1940, Rommel was given command of the 7th Panzer Division, later nicknamed Gespenster-Division (the "Ghost Division", due to the speed and surprise it was consistently able to achieve, to the point that even the German High Command lost track of where it was), for Fall Gelb, the invasion of France and the Low Countries.

posted by kirkaracha at 9:39 PM on July 29, 2005

Yes, I meant "lead" in the literal sense of "he was in front" -- presumably giving him a first-hand view of the effectiveness of the "thin crunchy shell" defense against modern armor.

This is why I've never fully understood why he pressed for moving armor closer to the shore in France. Given the lessons learned on the Maginot Line in 1940 and the class on how to defeat armor that Russia was putting on in the east, it just doesn't make sense to me -- dispersing armor toward the coasts would necessarily thin their ranks.
posted by event at 12:38 AM on July 30, 2005

Clarification: He's Erwin Rommel. I'm Piddly Pipsqueak. I'm not arguing that he was wrong -- I'm just saying that I don't understand his reasoning.
posted by event at 12:59 AM on July 30, 2005

One of the biggest things on our side was the dissension in German ranks regarding the invasion.

Not to mention that many of the German ranks were not even Germans, but Poles, Czechs, etc., that just couldn't wait to surrender to U.S. troops. In many cases, Eastern European conscripts took the sighting of Allied troops as the impetus to shoot their German c.o.'s & surrender.


Dunkirk: The most glorious defeat in the history of Britain. The BEF was getting slammed by the Germans, but they managed to return about 90% of the troops to British soil, using every means available from massive troop transports to small dinghies manned by civilians, all under constant attack by German artillery & air power. D-Day was the beginning of the end for the Third Reich, but without the successful retreat from Dunkirk, England would have been much more likely to fall prior to then.

posted by Doohickie at 12:48 PM on July 30, 2005

From Steven Ambrose's D-Day:

How on earth did Koreans end up fighting for Hitler to defend France against Americans? It seems they had been conscripted into the Japanese army in 1938--Korea was then a Japanese colony--captured by the Red Army in the border battles with Japan in 1939, forced into the Red Army, captured by the Wehrmacht in December 1941 outside Moscow, forced into the German army, and sent to France.

posted by kirkaracha at 2:30 PM on July 30, 2005

"Between 26th May and June 4th around 200,000 British troops and 140,000 French troops were evacuated from the beaches north of Dunkirk by relays of British and French ships, large and small. More than 40 naval and merchant vessels were sunk and 68,000 British troops were killed, captured or wounded in the three weeks of conflict. Many more French were killed, especially those defending the pocket to enable the retreat. Had Hitler not interfered with the wishes of the German military command after the panzer divisions reached Abbeville on May 20th, the pocket would have been entirely cut off from the sea and the defeat enormous. As it was, the British propaganda machine converted defeat into a curious example of pragmatic heroism. Both French and British myths about how they had each been let down by their respective ally were to poison relations for many decades."
posted by Oneirokritikos at 4:14 AM on July 31, 2005