What If - Stopping D-Day

It’s time for an invigorating round of historical ‘what if’.  The discussion portion of our recent post on Chinese amphibious capabilities took an inexplicable detour (as post discussions often do!) to debating what Germany could have done differently to defeat or prevent the Allied D-Day invasion.  The usual list of suspects was discussed including unified command and control, air superiority, better intel, etc. 

ComNavOps, always believing that the best defense is a good offense, suggested that, rather than waiting on the defensive and then trying to stop the assault, the Germans would have been better served to go after the buildup of troops, supplies, and equipment in England and stop the invasion at its source, before it ever started.  This is analogous to conducting ASW not by fighting subs out in the open ocean but by attacking the factories that produce the subs and the ports where they are serviced.  It’s easier to destroy the source of submarines and their support facilities than to battle them one-on-one at sea.

Had Germany been able to significantly impact the buildup, the invasion would have been indefinitely delayed.  Of course, this is easier said than done.  Let’s kick around some ideas and see if it could have been done.

D-Day - Could This Have Been Prevented?

First, it is necessary to understand that the Germans would not have had to destroy 100% of the men and materiel – an on-going destruction of, perhaps, 20% would likely have been sufficient to disrupt the training and buildup to the point of causing perpetual delays in the assault timing, thereby accomplishing the goal of ‘defeating’ the invasion before it ever began.

So, understanding the fairly limited scope of the task, what methods could the Germans have used to accomplish this task?

Strategic Bombing – Instead of focusing on bombing London, the Luftwaffe could have focused on troop, supply, and equipment concentrations.  Yes, men and material were dispersed across England but it’s impossible to prepare a D-Day size invasion and not have significant concentrations of men and materiel.  In fact, the very dispersal that was used, to the extent it was, would have worked against the RAF’s defensive efforts since they would have had to disperse their defending aircraft as well.

Recognizing that, ultimately, an amphibious assault depends on transport ships, the bombing should also have focused on the transport ships.  These would have been relatively known, fixed point locations and easy targets (neglecting, of course, the surrounding anti-aircraft (AA) defenses and RAF!).

It is also worth wondering if, instead of massed bombing attacks, the Germans should have engaged in smaller, low level, nighttime aircraft raids.  Launched against known depots, troop concentrations, and transport vessels, such raids ought to have been difficult to detect, nearly impossible to predict the targets, difficult to defend against, and fairly effective since total destruction would not have been the goal – 20% overall destruction should have been fairly easily achievable.

German Bombers Attacking Depots, Troop Concentrations, and Transport Ships

Commando Raids – The very short distance across the English Channel and North Sea (ranging from 60 miles at the SW end to a narrow point of around 20 miles at the Calais-Dover area and back out to 100 miles between Belgium/Netherlands and England across the North Sea) lends itself to undetected transport of small raiding units across the Channel.  Raids from Company down to squad size units would have been undetectable and difficult to defend against.  E Boats were able to routinely operate undetected in the Channel and nighttime, small transports would have been very difficult to detect and interdict.  Again, total destruction would not have been the raider’s goal.  Constant disruption would have sufficed to indefinitely delay the planned invasion.

German Brandenburg Commandos Attacking Allied Supply Depot

U-Boats and Mining – The Germans might have been better off concentrating a portion of their U-Boats not to direct sinking of ships in convoys in the mid-Atlantic but to continual clandestine laying/re-laying of mines at each port.  It doesn’t matter how many ships arrived from the US if they couldn’t get into a port to unload.  This would also have had the effect of avoiding direct combat with the Royal Navy (RN), thereby preserving U-Boats.  Of course the RN would have heavily patrolled the port approaches but without the U-Boats ‘announcing’ their presence in the form of revealing attacks, detection would have been much more difficult.  Extensive mining would also have taken a toll on the RN destroyers and rendered their defensive efforts much more difficult and dangerous.

Type TMB Mine Being Loaded Aboard U-Boat To Seal The English Ports

E Boats (Schnellboot) – German E Boats should have focused on finding and destroying landing vessels more so than merchant vessels or warships.  Sneaking near or into ports and sinking transports would have definitely caused invasion plans to be postponed.

E Boat Attacking Transport Vessels

Naval Bombardment – The time frame in question, here, is 1940-1944.  Especially during the early years, Germany had the use of Bismarck (later Tirpitz) and several heavy cruisers.  With co-ordinated support from the Luftwaffe, dedicated Luftwaffe anti-torpedo plane screens (English torpedo planes of the time were barely advanced beyond WWI levels and should have been easy prey for German fighters), E Boat screening, and U-Boat support and mining to prevent the British Home Fleet from approaching, bombardment raids aimed at the Allies transport vessels could have been conducted with a reasonable chance of success. 

Bismarck Attacking Transport Vessels

Shore Artillery – Though not capable of direct attacks on Allied men and materiel in England, shore artillery at the Calais-Dover chokepoint could have sealed the northeast entry to the Channel from RN naval forces.  The fact that such artillery was fielded and produced very little success wouldn’t have changed the thinking at the time that the RN couldn’t risk that approach.  Combined with mining, the northeast approach would have been secured from Allied naval intrusion thereby facilitating the above listed methods.

Calais-Dover Shore Artillery

Summation and Lessons for Today - With some effort and refocusing of priorities, the Germans could have turned the English Channel into an A2/AD zone and a fairly secure base from which to indefinitely disrupt the Allied buildup for the Normandy invasion. 

The major lesson to be gleaned from this is that defense, ultimately, seldom succeeds.  The best defense is a good offense.  This is relevant today for the US Navy.  Our entire fleet is heavily slanted towards defense (Aegis, AMDR, BMD).  Our carriers with their shrinking and short ranged air wings have almost reached the point of existing merely to protect themselves.  We have produced no offensive ship or weapon in decades.  Navy leadership has recently publicly acknowledged exactly this and now claims to be focusing on offensive operations – yeah, we’ll see.

Another major lesson is strategic thinking.  The German military’s strategic thinking was dominated by Hitler, personally, both in his explicit orders and the stifling effect he had on his military leadership.  No one ever accused Hitler of being a strategic genius.  Had Hitler not elected to attack Russia in June 1941, Germany would have had double the men and materiel to oppose the Allied invasion and would have been in a far stronger position to carry out the actions listed above.  Today, our military and Navy suffer from the same complete lack of intelligent strategic thinking.  Witness our absolutely floundering and nearly non-existent response to the Chinese annexation of the South China Sea.  Witness our complete lack of a military strategy for war with China.  We need to begin serious offensive strategic thinking and wargaming.

Mine warfare is another obvious lesson for us, today.  The power of mines has been demonstrated time and again throughout history and yet, for practical purposes, the Navy has no offensive mine warfare capability.  We need new, more capable mines and multiple ways to deliver them.  We need to integrate mine warfare into our operational planning (you know, whenever we get any operational planning).

This kind of ‘what if’ thought exercise is not only enjoyable but it offers insights and lessons applicable to our situations today.