From Small Causes, Great Events Part Six

Sea Lion vs Overlord


One of the favorite topics of alternative history (and one of the scenarios endlessly replayed in war games such as Axis & Allies and 3rd Reich) is what if Germany had attempted Operation Sea Lion. Assuming a Luftwaffe victory over the Royal Air Force in the Battle of Britain was Sea Lion feasible in other respects? Could Hitler have knocked the United Kingdom out of the war in the summer of 1940 or would the attempt have led to his first major defeat? This paper will compare and contrast Operation Sea Lion and Operation Overlord utilizing ten criteria essential to success in amphibious assaults – planning, materiel support, deception, intelligence, combined arms support, command structure, technology, innovation, sustainability and enemy defenses.


If the Blitzkrieg into Poland shocked the great powers, the complete collapse of France in just six weeks absolutely stunned the world.[1]  In June 1940 all that stood between the seemingly invincible Wehrmacht and total domination of Western Europe was the English Channel and 555,000 [2] badly shaken British, French, Dutch and Belgian troops evacuated from the continent. Its tanks, trucks, artillery and other heavy equipment abandoned on the beaches of Dunkirk the shattered remnants of the British army regrouped and frantically prepared as best they could to repel an amphibious assault. In centuries past protection against invaders had depended upon the wooden walls of the Royal Navy (RN). Survival now rested on resolute sailors serving aboard steel men-of-war and upon the indomitable courage of Royal Air Force (RAF) pilots and crews.

Four years later the glory days of Blitzkrieg were over, nothing more than the wistful memories of grizzled veterans shared with ever-younger recruits over evening cook fires. In the East the Soviet juggernaut pressed inexorably upon the borders of the thousand year Reich. In the South the Anglo-American Allies had driven Rommel out of North Africa, captured Sicily and in savage fighting were pushing relentlessly, albeit slowly, up the Italian peninsula. In the West the largest amphibious force ever assembled weighed anchor to breach Hitler’s vaunted Atlantic Wall and liberate Festung Europa (Fortress Europe).



Smashing the Atlantic Wall was a daunting task. As anyone who has ever conducted an amphibious exercise will attest just getting soldiers out of their racks, into landing craft and onto the proper beach on time and in some semblance of order is no mean feat. Coordinating Naval Gunfire (NGFS) and Close Air Support (CAS) adds another degree of difficulty. The multitude of organizational and logistic considerations involved in amphibious operations is staggering. Each element follows the preceding component in a strict timeline. Every function in the overall plan is interdependent, relying upon precise execution of all parts for success. Each factor offers an opportunity for Murphy’s First Law (Anything that can go wrong will go wrong) to intrude. Logistic complications alone can and do create dangerous confusion. Opposition, no matter how light, almost guarantees chaos. In that regard, although Festung Europa did not live up to Goebbels’ propaganda claims, German defenders in many places were well emplaced and highly motivated. When the first Allied soldier landed in Normandy however he did enjoy certain advantages – among them a comprehensive operational plan.

Planning and preparation for Overlord had been underway for over two years [3] drawing upon the lessons learned in North Africa, Sicily, Italy and the Pacific landings. The result was a massive document of extraordinary detail addressing every conceivable contingency. Prepared in an age well before computers it required a monumental effort and remains a remarkable achievement.

Overlord evolved from Operation Roundup, the proposed cross channel invasion scheduled for 1943. Roundup grew out of Operation Sledgehammer the highly problematic assault set for 1942. Both plans were tabled when President Roosevelt, eager to have American ground forces engaged anywhere in Europe as soon as possible, overrode the recommendations and objections of his Joint Chiefs of Staff (JCS) and cast his lot with Churchill who favored a ‘peripheral strategy’ in the Mediterranean. The strategic gains from Torch, Husky, Avalanche and Shingle are debatable but the lessons learned undeniably improved Overlord’s chances of success.

In the first iteration of Overlord the Chief of Staff to the Supreme Allied Commander (COSSAC) proposed a three-division assault supported by two Airborne Brigades. When Eisenhower assumed command of Supreme Headquarters Allied Expeditionary Force (SHAEF) one of his first decisions was to postpone the invasion by one month. Assault ships and landing craft were sliding down the ways in English and American shipyards in fantastic numbers. This brief delay allowed the Allies to gather sufficient amphibious vessels to expand the invasion force to five infantry divisions augmented by three Airborne Divisions. After factoring in the requirements for calm weather, a near full moon, a low tide beginning to flood and wide, flat beaches within fighter range of English fields, early June 1944 was selected as the most opportune time. Phase I called for the assault of “an initial lodgement area” [4] and the “capture of Caen.” [5] Phase II directed the “enlargement of the area captured in Phase I, to include the Brittany peninsula, all ports south to the Loire and the area between the Loire and the Seine.”[6] Phase III envisioned the follow on landing and subsequent breakout of Patton’s Third US Army.

Most importantly, every aspect of the landing plan was reinforced with realistic training conducted under the strictest secrecy. When the Allied forces went into combat on 06 June 1944 they were physically and mentally well prepared.

In start contrast to the meticulous Allied preparations the architects of the ‘master race’ did not have a viable master plan for defending the western portion of the Reich from invasion. The reason for this glaring oversight lies with the Fuhrer. Hitler well understood the Roman dictum Divide et impera (Divide and rule) and applied it to friend as well as foe. In the Byzantine world of Nazi Germany the different branches of the military and the various organizations of the state competed with one another for Hitler’s favor. This policy kept any one person or group from gathering enough power to challenge the Fuhrer but also resulted in great duplication of effort, waste and inefficiency. The Wehrmacht, Kriegsmarine and Luftwaffe each developed separate defensive plans. There was little cooperation or coordination between the services until one reached the very apex of the ruling hierarchy – Hitler himself, and he was all too fallible. Even within the Army there was no consensus on how best to defend the Reich. Rundstedt favored a mobile defense. He recommended placing the Panzer Divisions in a central reserve, containing the invasion and then delivering a concentrated counterattack. Based on his experience in North Africa Rommel had a greater appreciation for Allied air power. He felt the first forty-eight hours were critical, that the invasion would be stopped on the beach or not at all. Consequently he opted for a forward defense supported by immediate panzer counterattacks and positioned his forces accordingly. In a compromise guaranteed to satisfy no one OKW allocated three Panzer divisions to Army Group B, three Panzer divisions to Army Group G and three Panzer divisions and one Panzer Grenadier division to OB West. Although nominally under Rundstedt’s command the four divisions of the theatre reserve were actually under Hitler’s personal control. This lack of cooperation and coordination in both preparation and in the ensuing battle severely handicapped the German defense.

Materiel Support

In On War Clausewitz discusses offensive momentum in terms of a culminating or balance point. In any campaign or battle offensive power decreases as resistance increases. This process continues until the aggressor achieves victory or his forces are exhausted and a stalemate ensues. Clausewitz’s concept of a culminating point is especially applicable in an amphibious assault. To ensure the Allies achieved and maintained offensive momentum the United States assembled twenty-one divisions (13 infantry, 6 armored and 2 airborne) for Overlord. By D + 90 there would be 1,200,000 American troops and 250,000 American vehicles in France. In addition the British and Canadians contributed another seventeen divisions (10 infantry, 5 armored and 2 airborne) to the effort.

To prevent an equally rapid build up of German forces SHAEF dedicated the entire U. S. Army Air Force to Overlord. Under the TRANSPORTATION PLAN portion of Overlord the 2700 fighters, 1956 heavy bombers, 456 medium bombers and 171 light bombers of the 8th strategic air force and 9th tactical air force were committed to isolating the invasion area. In Phase I Luftwaffe planes, aircraft factories, repair depots and storage parks were targeted. In Phase II American planes attacked railroad tracks, trains and yards. In Phase III bridges were destroyed isolating France below the Seine. So complete was Allied air supremacy and so effective were the attacks under the Transportation Plan that German reinforcements were forced to travel only at night. Movements that previously would have taken a few days stretched into weeks.


As part of the deception plan Allied planes continued to bomb other areas of France and the Low Countries as well as targets in Germany. Another subset of the Overlord Plan, Operation Fortitude involved the creation of an entire and entirely fictitious First U. S. Army Group (FUSAG) allegedly commanded by General Patton. Dummy tank, truck and artillery parks were constructed. Phony encampments were created. Signal Corps personnel filled the airwaves with false information concerning diversionary attacks in southern France and Norway in preparation for the main thrust at Pas-de-Calais. Since this ‘intelligence’ matched Hitler’s preconceived notions of the inevitable invasion Operation Fortitude was noteworthy success. Essential reinforcements were pinned in place during the critical first weeks of the Normandy campaign. In addition severe weather, which delayed the Allies until 06 June, also lulled the German defenders into a false sense of security.


Although there were glaring oversights in Allied intelligence [7] two major intelligence coups significantly contributed to Overlord’s success. The first was ULTRA. By 1944 the Allies had broken the Enigma code and were able to read German message traffic giving them a good picture of enemy dispositions and intentions. The second was DOUBLE CROSS. At the time of the Normandy invasion all Axis spies in England had been turned. Now working as double agents these operatives feed their handlers false information about attacks in Norway and the Pas-de-Calais.

With its spy ring turned and the Luftwaffe unable to penetrate English air space for reconnaissance Germany operated in an information vacuum. Invasion was inevitable but the crucial questions of ‘when’ and ‘where’ remained conjecture. As a result Hitler was forced to defend 2800 miles of coastline guaranteeing Allied superiority at the point of attack. As Frederick the Great noted, “He, who defends everything, defends nothing.”

Combined Arms Support (CAS)

Although the Allies dedicated 6,000 ships and landing craft and 13,000 aircraft to the invasion CAS was not as effective as it should have been. British landing policy stressed tactical surprise. American amphibious doctrine emphasized overwhelming firepower. In a flawed compromise neither was achieved. Landings were conducted in daylight negating the advantage of shock. A brief preliminary bombardment (only 35 minutes at Omaha beach) did little more than alert the defenders. Saturation attacks from landing craft modified to carry rockets (LCT(R)’s) were thrown off target due to high surf conditions. Finally, because of cloud cover, pilots delayed bomb release several seconds. As a result their payloads fell well inland. On the positive side the Allies did gain complete air superiority preventing any counterattacks by the Luftwaffe and daring destroyer captains ran their vessels nearly aground in order to deliver highly effective counter battery fire at point blank range. Overall however, it was junior officer and senior NCO initiative that carried the day.

Command Structure


Supreme Commander Allied Expeditionary Force – General Eisenhower
Deputy Supreme Commander – Air Chief Marshal Tedder
Chief of Staff – Lt. General Bedell-Smith
Allied Naval Expeditionary Force – Admiral Ramsay
Allied Expeditionary Air Force – Air Vice Marshal Leigh-Mallory
Commander 21st Army Group – General Montgomery
1st U. S. Army – Lt. General Bradley
2nd British Army – Lt. General Dempsey

Second in importance only to the immense scope of the Allied invasion plan and intense preparation prior to D – Day was the rigidly organized and thoroughly integrated command structure of the invasion forces. The disparate elements were subordinated to the Supreme Commander. Outwardly affable, Eisenhower was an iron willed, highly capable officer and a fortuitous choice. Years of experience as a staff officer under MacArthur and Marshall served him and the Allies well in this post. As should be expected on a joint and Allied command personality conflicts abounded and staff meetings were frequently acrimonious. When final decisions were made and orders given however, they were saluted smartly and dutifully executed.



Admiral Doenitz


Reichsmarschall Goering

Naval Group West [8]
Admiral Krancke
OB West
Field Marshal von Rundstedt
3rd Air Fleet [9]
Field Marshal Sperrle

Army Group B – Field Marshal Rommel

Army Group G – Col. General Blaskowitz

15th Army – Col. General Salmuth
7th Army – Col. General Dollman

1st Army
19th Army

*Hitler rather than Rundstedt maintained direct control of mobile theatre reserves, which could not be released without his personal authorization.

Lack of a coordinated plan of defense and a convoluted chain of command ensured the 58 divisions [10] available to Rundstedt were slow to react during the critical period after the initial landing and were later fed piecemeal into the battle for Normandy.


In a remarkable achievement German engineers fielded V-1’s, V-2’s and jet aircraft. These potential war winners came in limited numbers however and far too late to alter the outcome of the conflict. Allied industry far surpassed German efforts where it counted, in mass production of basic but nonetheless critical technology. Two examples will serve. The first was shallow draft landing craft. The availability of thousands of LCV/P’s, LCI’s, LCC’s, LCA’s, LCT’s, LCT(R)’s and LST’s patterned after the Higgins Boat allowed the Allies to put 150,000 men plus supporting equipment on the beach on D-Day [11] overwhelming the German defenders. More importantly these ubiquitous craft ensured the Allies won the race to build up combat power.[12] Secondly, Hobart’s Funnies (British and American tanks adapted for swimming, bridge laying, mortar launching, flame throwing, track laying and mine destroying) added crucial firepower on the beach and greatly assisted rapid movement inland in the 2nd Army sector.


Perhaps the most ambitious and impressive Allied innovation in Operation Overlord was the MULBERRY, the creation of all weather artificial harbors at Vierville and Arromanches on the Normandy coast capable of handling 5000 long tons of supplies and 1000 vehicles per day. Eighty-nine GOOSEBERIES (derelict ships) and 150 PHOENIXES [13] (concrete caissons) were scuttled to form an outer breakwater. BOMBARDONS (steel floats 200 feet long) were anchored to create an inner breakwater. When completed these barriers sheltered twenty-one miles of formerly open shoreline providing protected anchorage for large cargo ships. A constant stream of barges and small craft shuttled to and from these anchored supply ships and the shore. LOBNITZ PIERHEADS (floating docks) created piers that allowed LST’s and small cargo ships to unload directly into trucks. WHALES (steel pontoons) formed causeways from the piers to the beach expediting the movement of supplies to the front. Unfortunately severe gales during the period 19 – 22 June destroyed the Mulberry at Omaha Beach and damaged the harbor at Gold Beach. Only the British Mulberry was repaired exacerbating the need to capture Cherbourg and other French ports as rapidly as possible. In the interim LST’s were grounded at high tide and hurriedly offloaded before the tide returned. In spite of Herculean efforts supply never kept up with demand. Operations would be hamstrung by logistic shortfalls (especially POL) until Montgomery finally captured Antwerp.


To ensure the offensive momentum gained on D-Day continued the Allies identified fifteen French ports for early capture and reconstruction. The Overlord planners also realized the Transportation Plan, which had so effectively hindered German reinforcement would also impede an Allied breakout. Therefore 1,548,000 man-days were allocated for road, railroad and bridge reconstruction. The staggering amount of material and equipment laid up for this effort is indicative of the forethought and thoroughness that went into Allied preparations:

11,700 long tons of construction equipment
15,800 long tons of asphalt
112,000 tons of bridging
800 standard fixed Bailey sets
250 standard pontoon Bailey sets
175 heavy increment Bailey sets
165 heavy pontoon increment sets

In addition plans were made to deliver 5000 tons per day of Petroleum, Oil and Lubricants (POL) at D+20 and 10,000 tons per day by D+90. Part came by tanker and part by PLUTO (Pipeline Under the Ocean) another aspect of the Mulberry project. These figures proved inadequate and POL became the Achilles Heel for the British and Americans. The Allied advance literally ran out of gas in late autumn allowing the Germans to regroup and launch their last major offensive of the war in December.

Enemy Defenses

Fuhrer Directive number 40 ordered the creation of an ‘Atlantic Wall’ stretching from Spain to Norway. Covering some 2800 miles this series of fortifications was one of the largest construction projects in human history. Special emphasis was given to the Pas-de-Calais, the shortest route from England to France and most direct line of march from the landing site into the German heartland. Significantly this was the only area completed by June 1944. Recognizing the vital importance of harbor facilities to any invasion Hitler also insisted each port city be heavily fortified and strongly garrisoned. Typical of operations in the Third Reich part of the work was undertaken by Organization Todt, part by the Army, part by the Air Force and part by the Navy with no coordination of effort. Consequently when Rommel made his first inspection tour in the fall of 1943 he found the wall to be, in his words, “a figment of Hitler’s Wolkenkucksheim” (cloud-cuckoo-land). Of the 23,000 structures erected approximately half followed some standard design. The remaining bastions were built haphazardly per strictly service needs or local commanders discretion. Little or no thought was given to integrating defensive systems or coordinating efforts.

Rommel set about to immediately rectify the situation. At his command Army units dedicated three days per week laboring to improve fortifications. Hedgehogs [14], Belgian gates [15] and stout wooden posts angled toward the sea, all topped with mines, were erected in the tidal zone. Soldiers strung hundreds of miles of barbed wire and laid millions of mines designed to channel invasion forces into killing zones. Artillery was calibrated, firing arcs established and machine guns emplaced to sweep the beaches. While not yet complete, by June 1944 the Atlantic Wall had been vastly improved. As necessary as this work was it did impact combat readiness. Work and guard details left little time for training. This was a reasonable trade off however considering Allied mastery of the sea and air.


Although intelligence, CAS and sustainability were less than perfect the overall concept and execution of Overlord was overwhelming. The Normandy invasion was a masterpiece of strategic planning made possible by the astonishing capacity of British and, especially, American industry. The sheer scale of the operation staggers the imagination.

Its size should have been Overlord’s weak link as well. Storage facilities, vehicle parks, encampments, embarkation ports and the invasion fleet underway in the channel were fat targets. A decisive blow at the POL dumps for example would have set the invasion back for several months. Fortunately for the Allies interdiction by the Kriegsmarine was not feasible and the major portion of the Luftwaffe was tied down on the Eastern Front. Thus Hitler lost his best chance to stop the attack. Given the sate of the Wehrmacht on the Western Front and the command problems between OKW, OKH and OB West once the Allies were ashore eventual defeat was only a matter of time.



When France fell in June 1940 Britain would never again be more vulnerable. A successful invasion of England at that point would have ended the war on German terms. Yet, in spite of massive rearmament programs during the 30’s and a dominant tactical doctrine in the form of Blitzkrieg, Germany did not possess the where with all to capitalize on its amazing good fortune. No contingency plans had been prepared for such an eventuality. Even if they existed, the Kriegsmarine was totally inadequate to the task. The reasons for Germany’s lack of military readiness at sea were political and philosophical. Politically Hitler never envisioned a long-term war with Britain, much less an invasion of Albion. Faced with German mastery of the continent he expected the “nation of shopkeepers” to be sensible and come to terms. To understand the philosophical reasons for the state of the Kriegsmarine it is necessary to digress a bit. Unlike Kaiser Wilhelm II who studied Mahan and invested heavily in the High Seas fleet, the work of General Doctor Karl Haushofer [16] swayed Hitler’s strategic view. According to Haushofer’s theories of Geopolitik the growth of motorized road and railroad transport negated England’s historic control of the sea. In Haushofer’s view mastery of the European heartland was central to world domination. These geopolitical ideas dovetailed neatly with Hitler’s quest for Lebensraum, racist theories of Aryan superiority and pathological anticommunism. Since Hitler’s strategic aims lay on the continent the Wehrmacht and Luftwaffe received top priority. As an ancillary service the Kriegsmarine rearmed under the much more modest Plan Z. Adopted in 1938 Plan Z called for a balanced fleet of capital ships and submarines. War was not anticipated until 1943 or 1944. On 27 January 1939 the Naval rearmament schedule was extended to 1949. When Germany invaded Poland in September 1939 naval planners were aghast. [17] Naval construction immediately shifted to U Boats but the war was ten years too early and the change in priorities ten years too late. The Kriegsmarine entered the war with 2 new battleships, 2 old battleships, 3 pocket battleships, 1 heavy cruiser, 5 light cruisers, 17 destroyers and, fortunately for the Allies, only 56 submarines. In addition 2 battleships, 1 aircraft carrier (never completed), 4 heavy cruisers and 1 light cruiser were under construction. While the Army and Air Force may have been adequate for Sea Lion the Navy’s assets were insufficient to engage the British fleet or wage economic (U Boat) warfare. Lack of a Naval air arm (Goering covetously guarded all air assets) also hampered the operational effectiveness of the Kriegsmarine.

In addition to the political and philosophical problems resulting in an under strength Navy and inadequate planning and preparation time,[18] inter-service difficulties also emerged. The Army saw Operation Sea Lion as nothing more than a large river crossing in which the “Luftwaffe will do the work of artillery, while the Kriegsmarine will do the work of engineers.” Through sheer audacity and at great cost the Kriegsmarine had barely succeeded in Norway. Consequently, the Navy possessed a far more realistic assessment of the difficulties involved in Sea Lion. All depended upon the Air Force however, and, as always, Goering pursued his own agenda.

The final proposal (the word plan carries too strong a connotation) called for the Navy to:

• Block the west end of the channel with U Boats
• Block the east end of the channel with mines and E Boats
• Sortie the main surface fleet into the North Atlantic to draw off the British Home Fleet

After crossing the channel in open barges the army would land and immediately capture a port in order to land Panzers. Second only to air supremacy the early introduction of armor was critical to victory against a numerically superior foe.

Only one training exercise was conducted. The results are quite revealing. Off Boulogne, in good weather and good visibility, with no navigation hazards or enemy defenses to contend with, of fifty vessels committed less than half managed to land their troops at H Hour. One tug lost its tow. One barge overturned when too many soldiers crowded on one side. Several barges broached in the surf and landed broad side to, unable to lower their ramps. The results of the fifty-barge exercise did not bode well for a 1277 barge assault on England.

Materiel Support

In 1940 / 41 the average German infantry division required 100 tons of supplies per day while engaged in combat. The average Panzer division consumed 300 tons of materiel per day when on the offensive. To land five divisions the Allies gathered 6000 vessels and vast stockpiles of provisions. To move nine divisions and sustain them for the first eight – ten days when the second wave was scheduled to land, the Navy gathered 170 cargo ships, 1277 barges and 471 tugs [19] in French ports. The barges immediately became targets for the RAF. They needn’t have bothered. Most of the barges were designed for river traffic and would sink in anything greater than sea state two. On D-Day men and equipment loaded in open barges were to steam in column until ten miles from the landing site, then turn sequentially and steer parallel to the coast. Upon signal all vessels were to execute a flank turn and proceed in line abreast to the beach. This intricate maneuver by barges under tow would take place at night with minimal lighting, controlled and coordinated by loud hailer! Rough weather, the Royal Navy and the Royal Air Force not with standing, Sea Lion was a recipe for disaster.


German capabilities or the lack thereof determined the possible landing sites as clearly to the British as to the Germans. Landing at night was the only deceptive measure adopted for Sea Lion.


Through their spy network the Germans were well informed as to British dispositions and capabilities. In view of German limitations however, this knowledge was of little value.

Combined Arms Support (CAS)

Since the Kriegsmarine would act to decoy the Home Fleet NGFS was not a factor in Operation Sea Lion. Delivery of Combined Arms Support fell solely upon the Luftwaffe. Simultaneously the Air Force was required to:

• Keep the Royal Navy out of the channel.
• Win total air superiority.
• Interdict British reinforcements moving by rail.
• Conduct a mass attack on London in order to force the civilian population to flee choking the road net.

A tall order considering at this point in the war the Luftwaffe mustered only 1260 bombers, 316 dive-bombers and 1089 fighters while the RAF carried 672 fighters on its Order Of Battle.

Had the Luftwaffe been successful in its bid for air supremacy Air Chief Marshal Sir Hugh Dowding was prepared to pull the 11th fighter group out of range until the landings began. He then planned to sortie from the Midlands with the combined strength of the 10th, 11th and 12th fighter groups in conjunction with the Royal Navy. Due to geography the Luftwaffe had no chance to complete its overall mission.

Command Structure

As noted previously each service vied with the other for Hitler’s favor. Raeder fought, justifiably, to expand the Navy. Goering schemed to enlarge the Luftwaffe to match his own immense girth. (Dunkirk, the Battle of Britain, air supply of Stalingrad, Luftwaffe field divisions and the Herman Goering Panzer division were monuments to his ego and testimony of his influence with Hitler.) Within the Army, Panzer generals argued with more conservative infantry generals over strategy and the Waffen SS competed with standard Wehrmacht units for men and materiel. As a result command relationships within and between the services were often strained and operations suffered accordingly. With regard to Sea Lion at a 31 July 1940 coordination meeting called by Hitler himself Luftwaffe representatives did not attend and, as discussion moved to purely Army matters, Admiral Raeder walked out.


The Germans applied no new technology to overcome the numerous obstacles involved in Sea Lion.


Other than paratroops the Germans introduced no innovations that might have improved the chances for success.


Sustainability is defined as massive long-term materiel support. As Theodore Gatchel writes in At the Water’s Edge an invasion is a race between the attacker and the defender to build up combat power. Considering the German scheme for the initial landing and follow on support Sea Lion was a race the Wehrmacht could not win.

Enemy Defenses

Although faced with the same time constraints the British came up with a far superior defensive plan. The Royal Navy and Royal Air Force plans were identical – preemptive attacks on staging areas, interdiction at sea and all out assaults at the landing points. In the same period the Army refitted the survivors of Dunkirk, organized a Home Guard, created beach defenses and set up stop lines, backed by mobile reserves. These preparations should have been more than adequate to turn back the surviving barge loads of seasick soldaten.


The Luftwaffe proved inadequate against surfaces ships at Dunkirk sinking only thirteen destroyers and damaging another nineteen in a confined area as they loaded troops. It proved equally incapable against the RAF during the Battle of Britain losing 1887 aircraft of all types in exchange for 1547 fighters. Clearly the Luftwaffe could not stop the RAF or the RN much less both.

The German invasion of Crete is instructive vis-à-vis Sea Lion.[20] Reinforcement and supply by sea proved impossible even though the Luftwaffe had absolute air superiority. The Royal Navy intercepted and utterly destroyed the first flotilla of small boats hazarding the crossing from Greece. No further attempts were made to reinforce by sea. Instead the 5th Mountain Division troops were flown in. Although they eventually prevailed German parachute and glider troops and the JU-52 transport arm of the Luftwaffe were decimated in the process. One can imagine the slaughter had the RN and RAF run through 1277 barges loaded with men and equipment during the proposed Sea Lion channel crossing.

Although it did not appear so at the time Sea Lion was never a viable military option. At best it was a propaganda ploy, a political threat that might have brought a timorous leader like Chamberlain to the negotiating table but never a tenacious warrior such as Churchill.


As discussed in Parts I and II, in every category except defenses – planning, materiel support, deception, intelligence, combined arms support, command structure, technology, innovation and sustainability – Allied preparation for Overlord was far superior to German efforts in the same areas during Sea Lion. Certain specific concerns within those general categories also stand out as tabulated below:

Overall Mission Commander
Coordinated Planning Staff
Sound Amphibious Doctrine
Practical Experience
Air Superiority
Sea Control
Purpose built landing craft
Heavy lift capability
Sea Lion

In World War II the Germans were notorious for operating on a shoestring and early on frequently succeeded due to the shock value of Blitzkrieg. This must have been the expectation since, for Sea Lion to be successful; England would have to collapse as France had in June 1940. Great Britain proved more resilient than France however. Consequently, in an extended operation, German planning and preparation would have been woefully inadequate. Nor did Hitler learn from Sea Lion. One year later he invaded the Soviet Union convinced it would fall in one summer campaign. True to form, as the struggle drug on, German planning and preparation, especially in the area of logistics, proved inadequate for a sustained operation.

The Anglo-American Allies tended to the other extreme. Operations were constrained by logistic concerns and senior leaders were frequently criticized for tentative strategic movements and failing to respond quickly to fleeting tactical opportunities. Montgomery, for example, talked boldly but was a meticulous planner and absolutely would not budge until every biscuit was in place.

There are advantages and disadvantage to both methods and valid reasons why Germany operated as it did. When a soldier or marine hits the beach in an amphibious assault however, especially considering what was at stake in 1940 and 1944, he deserves every advantage detailed planning can afford. In this respect the Allies succeeded whereas the Germans were fortunate indeed Sea Lion never came to pass.

* * *


[1]. At the time France was considered the worlds leading military power.

[2]. 340,000 from Dunkirk (Operation Dynamo), another 215,000 during Operations Aerial and Cycle, the evacuation of Le Havre, Cherbourg, St Nazaire, etc.

[3]. Initial planning for Overlord began after the Casablanca Conference. An Anglo-American staff led by Lieutenant General Sir Frederick Morgan completed the bulk of the work prior to Eisenhower’s appointment.

[4]. Outline of Operation Overlord, Section VIII, Part I, Tab I. U. S. Army Center of Military History, Historical Manuscripts Collection 8-3.4 AA v. 7

[5]. ibid.

[6]. ibid.

[7]. Allied intelligence failed to locate and identify important German units in the defensive Order of Battle (OOB) most significantly the 352nd Infantry Division at Omaha Beach. Allied planners also overlooked the military significance of the hedgerow terrain inland.

[8]. To oppose the 6000 ships in the Allied Armada, Naval Group West mustered 17 submarines and a few destroyers and E (torpedo) boats.

[9]. Arrayed against the 13,000 planes that flew on D-Day, 3rd Air Fleet listed 891 aircraft in its OOB of which only 497 were fully operational.

[10]. 33 static defense units, 13 infantry, 2 airborne, 9 panzer, and 1 panzer grenadier many of which were new divisions fitting out or units recovering from service on the Eastern Front.

[11]. These numbers swelled to 330,000 men and 50,000 vehicles by 12 June and 660,000 men by 30 June.

[12]. The importance of landing craft cannot be overstated. No less an authority than General Eisenhower stated, “Andrew Higgins is the man who won the war for us. If Higgins had not designed and built those LCVP’s, we never could have landed over an open beach. The whole strategy of the war would have been different.”

[13]. In preparation for Overlord shipyards in England employed 20,000 men around the clock to build 150 Phoenixes, hollow concrete blocks 200 feet long, 60 feet wide and 60 feet high. These were towed to Normandy, carefully positioned and scuttled to form a breakwater.

[14]. Hedgehogs – star shaped, six-foot obstacles, constructed of steel girders and topped with mines.

[15]. Belgian gates – large pieces of steel ten feet high set perpendicular to the beach and topped with mines.

[16]. Born 27 August 1869 Karl Haushofer was a professional soldier whose superior intelligence earned him an appointment to the General Staff. Retiring in 1919 as a Major General, Haushofer dedicated himself to the regeneration of Germany. Turning to education he combined the theories of Ratzel, Kjellen and MacKinder developing a doctrine he called Geopolitik. In 1922 he founded the Institute of Geopolitics in Munich and through his student, Rudolph Hess, profoundly influenced Hitler during the formative period of the Nazi party.

[17]. “Today the war against France and England broke out, the war which, according to the Fuhrer’s previous assertions, we had no need to expect before about 1944. As far as the Navy is concerned, obviously it is in no way very adequately equipped for the great struggle with Great Britain by autumn 1939. The submarine arm is still much too weak to have any decisive effect on the war. The surface forces are so inferior in number to those of the British fleet that they can do no more than show that they know how to die gallantly.” Admiral Erich Raeder.

[18]. The order to begin planning was not given until 02 July 1940, allowing only 84 days prior to the proposed invasion date.

[19]. Diverting so many cargo vessels and river ferries greatly disrupted commercial traffic in the Baltic and on the Rhine.

[20]. The parallels between Sea Lion and Operation Merkur are striking. The invasion of Crete also suffered from a very short planning period and relied on commandeered caciques (small two masted fishing boats with an auxiliary engine) assembled at Piraeus for reinforcement and supply. British destroyers annihilated the first flotilla. No second attempt at sea borne landings or supply was made. Although they prevailed the resulting shortage of heavy equipment, transportation and supplies cost the air and glider borne troops dearly.