In 1938, Germany had only 3 “pocket” battleships, 6 light cruisers, 7 destroyers, 12 torpedo boats, and 36 submarines—many of which were unfit for ocean service. The British Home Fleet alone had: 15 battleships, 62 cruisers, 7 aircraft carriers, 178 destroyers, and 56 submarines. As the war drew closer, German naval planners were convened by Adolf Hitler to prepare for a possible war with the world’s premier maritime power, Britain. German Admiral Erich Raeder, traditionally an opponent for Germany’s aggression toward such a powerful naval foe, appointed a planning committee to lay out the best course of action that would allow the German Navy to compete with the Royal Navy. Raeder placed his confidence in a young naval officer, Commander Hellmuth Heye.
With time certainly not on Germany’s side, Heye offered two options. Germany could undertake the long-term construction of a full battle fleet, or she could undertake a short-term program to create the basis of an effective sea war. Heye advocated, along with Rear Admiral Werner Fuchs, that the short-term program be centered on a cruiser fleet with accompanying “pocket” battleships that readily “could in the event of war present a considerable threat to Britain’s lifelines”. Conversely, Dönitz argued for the construction of a U-boat fleet. Raeder, in writing up the committee’s recommendations to Hitler, tailored the report to sell the Führer on what became known as the infamous “Z Plan”, a massive shipbuilding program that sought to have a mighty and diversified battle fleet by late 1944 or 1945; as the “Z Plan” was duly approved in January of 1939. Raeder had promised that his plan “could not only threaten Britain’s lifelines but also engage the British High Seas Fleet with every prospect of winning”, but warned Hitler that “If war breaks out in the next year or two, our fleet won’t be ready.”
For Germany, arguably its most valuable method of attacking or even hindering British maritime communications during World War II was through the use of its small but growing combined fleet. While too weak to bring the British fleet to a decisive battle, or impose a fleet blockade, it could effectively bog down the Royal Navy by utilizing a fleet-in-being strategy. Realistically, Germany could concede that it was a hopeless objective to gain or achieve command of the sea, but it could deny Britain sea control by serving as an ever-present threat. Raeder summarized the early German fleet-in-being approach by stating “Enemy naval forces, even if inferior in strength, are only to be attacked if this should be necessary to achieve the main objective. Frequent changes in the operational area will provide uncertainty and delays in the sailing of the enemy’s shipping, even if no material success is achieved. The temporary disappearance of German warships in remote areas will add to the enemy’s confusion.”
It was here that Germany’s fleet-in-being approach during the first few years of the war served it greatly. By 1940, it was just strong enough under its collection of small battleships and cruisers that the risk of attacking it was still deemed to be too great for the Royal Navy, allowing the German Navy to establish its presence, without risking the decisive battle that could place its existence in peril. Regarding the German fleet-in-being, particularly when including Tirpitz, Winston Churchill later stated that “It exercises a vague general fear and menaces all points at once. It appears and disappears causing immediate reactions and perturbations on the other side.”
The British greatly feared the escape of German warships into open water, as was seen when the “pocket” battleships Admiral Graf Spee and Lützlow permeated into the North and South Atlantic in December of 1939, as well as the frenzy to catch the Bismarck and Prinz Eugen made it to the Atlantic in May of 1941. However, in doing so these valuable and limited resources were divorced from the protective screen of U-boats and the necessary air cover from the Luftwaffe. The virtually independent forays into distant enemy waters and the navally disastrous loss of two cruisers, seven destroyers, and the year-long laying up of the Lützlow during the April 1940 invasion of neutral Norway, foreseeably led to the decline of the German fleet-in-being.
In the Arctic and North Sea, the effects of the eradication of the German fleet-in-being were easily discernible. It is here where it was witnessed that the ruler of the surface always and unquestioningly dominated surface maritime communications, that a successful naval offensive required the use of surface warships. As Britain and the United States funneled critical aid into the Soviet Union through the Arctic to supply its budding 1942-43 offensives starting with the recapture of Stalingrad and continuing on to a decisive victory at Kursk, the German Navy attempted to use its remaining surface fleet to halt the massive Allied convoys, seeking to offer some semblance of sea denial.
In July of 1942, the poorly escorted Allied convoy PQ-17 traveled through the Arctic was massacred as the Admiralty, on the belief that the Tirpitz was headed to intercept, ordered the convoy to scatter making it easy prey for U-boats and Norwegian-based Luftwaffe craft. This disaster resulted in the Allies adopting a more flexible and proficient escort system based around carriers, corvette and freely maneuvering cruisers themselves with destroyer escorts, which provided an almost impenetrable screen for U-boats.
The German surface fleet, after having the Tirpitz laid up yet again in late 1942 and losing the Scharnhörst in December of 1943, and its few remaining surface ships were withdrawn back to Germany for the remainder of the war. Raeder resigned in disgust with U-boat chief Admiral Dönitz succeeding him. Without the aid of surface ships the remaining U-boats in the Arctic proved unable to interrupt the convoys as it required the penetration through several thick layers of escorts. In total some 1,526 ships in 77 convoys replenished the Soviet war effort, with the Germans only sinking 98 ships. This was less than 7% of total shipping through the Arctic, a figure well below the level necessary to stall out the Soviets’ westward drive.
The horrendous mismanagement and continued erosion of the German fleet-in-being placed an increasing share of the Kriegsmarine’s responsibilities on its old standby, the U-boat. While U-boats had proven themselves useful tools in attacking military power as was demonstrated in October of 1939 when U-47 penetrated the Scapa Flow and sunk the British battleship Royal Oak, they were now pushed into near sole possession of carrying the bulk of the attack on British maritime communications. A heavy load that their numerical and operational limitations ensured they could not carry.
The U-boat fleet not only had to attack its enemy’s military strength by attempting to replicate fleet action in order to bottle up the Royal Navy in particular, but it also had to undermine its opponents’ war economies by attacking convoys. Undoubtedly, the Guerre de Course was a suitable role for U-boats. Their ability to slip through an enemy blockade and target vulnerable vessels provided Germany with an effective means of reducing the finances, resources, and production capacities of its chief logistical rival, Britain.
Between September 1939 and March of 1940, the meager U-boat fleet in service sunk nearly 900,000 tons of Allied cargo, outpacing its surface commerce raiders. Through 1941, with Dönitz’s “wolfpack” tactics firmly in operation, the growing German U-boat fleet sank some 496 merchant ships accounting for approximately 2.4 million tons of cargo. 1942 saw even larger gains, with 1,006 merchantmen sunk and nearly 5.5 million tons of cargo sent to the bottom of the Atlantic. In total, U-boats sank over 2,800 Allied vessels, causing a loss of nearly 14 million tons of cargo.
On its face, it would appear that U-boats were a stunning success; however, I submit that the aforementioned results are largely misleading. From the outbreak of the war in September 1939 through the latter portion of 1942, the incredible results of U-boat activity in hindering Allied maritime communications can be linked to several factors. Firstly, until the sinking of the Bismarck in May of 1941, Germany still had a serviceable fleet-in-being that could stymie British sea control in the North Atlantic. With the British largely concerned about runaway surface combatants, U-boats were able to “fly under the radar” so to speak. Secondly, from December of 1941 well into 1942, the Americans entered the war without implementing certain safeguards on their transatlantic shipping. They did not immediately organize their merchant vessels into convoys, nor did they enforce blackouts on their coastal cities, making their merchantmen easy victims for U-boats. Thirdly, until 1943 the Luftwaffe, although often disjointed from naval operations, provided the air cover required by U-boats to operate freely, if not enjoy shelter at port. When these layers of protection were no longer present, U-boat returns per ship lost dropped drastically as tactics and technology caught up to them.
This breakdown of Axis power and their ability to challenge Allied maritime communications openly manifested itself in the Mediterranean. With the French exit and Italian entrance into the War in the summer of 1940, the Mediterranean became severely inhospitable to Britain. Large swaths of the Mediterranean were within the range of the Italian Air Force, which by 1941, was reinforced by the Luftwaffe as Germany worked its way into Greece. Through much of 1942, Axis air superiority decimated British air bases and submarine pens on Malta, and its fleet at Alexandria. However, as the Italian fleet gradually faded due to Allied attacks and a general unwillingness to engage an often inferior British fleet, supplies from the eastern reaches of the Empire poured through the Suez Canal. As U-boats became increasingly ineffective at halting convoys from the British mainland and North America near the Strait of Gibraltar and the Luftwaffe was depleted by operations on the Eastern Front, the Allied war effort in the Mediterranean and in North Africa was rejuvenated. After the Italian surrender in September of 1943, Allied domination of maritime communications in the Mediterranean was complete.
The battle for maritime communications in the Atlantic ebbed and flowed, and could at times be less than straight forward. Yet, it cannot be denied that it was crucial in determining who emerged from the war victorious. Germany wasted its chance at truly stifling Allied maritime communications. These monumental failings led to the multi-front squeeze on Germany through: the survival and reinvigoration of the USSR, the resurgence of Allied efforts in North Africa and Italy, and the depletion of defenses in Western Europe, all of which doomed Germany.
In the Pacific the situation was less convoluted, the general strategies of the two major belligerents in the Pacific Theater never really deviated far from where they began. After the attack on Pearl Harbor on December 7, 1941, the United States launched itself into action to strangle the expansive Japanese Empire. Nicholas Tracy concluded that “naval action to deny an enemy the use of the sea for his trade is a strategy which only has decisive military and political significance when it is undertaken by the strong against states which are at once weak and economically vulnerable.” Indeed the Imperial Japanese Navy was far from weak, having recently driven the British from the South Pacific and having obliterated the U.S. Navy’s Pacific Fleet, yet the economic supply chain laid exposed, presenting a viable target for rebuilding navy powered by an unrivaled industrial base.
As Japan swallowed Anglo-French-American holdings in the Pacific, it overlooked the critical requirement of being an island empire, that such an empire cannot survive without its maritime communications. The British Empire had survived World War I and would survive the Second World War because it defeated the German U-boat threat, thereby, preserving its maritime communications. Japan made no such effort to defeat the unrestricted submarine warfare that the United States had levied against it following Pearl Harbor.
The American submarine action was a blend of offensive and defensive forms of naval warfare, Guerre de Course and the blockade. The Japanese response to such an American strategy was for the first several years of the war to have no response at all. Japan banked on the war taking an almost “Mahanian” trajectory with a short campaign dictated by a series of decisive battles culminating in a planned duplication of the 1904 Battle of Tsushima; therefore, the protection of its maritime communications was not worthy of discussion, much less any planning.
In such foolish thinking, Japan had made a lethal mistake. The United States Navy was entirely unwilling to indulge the Japanese Imperial Navy, opting to use its submarines to choke off the war economy of the Japanese homeland, thus slowly starving its forces scattered throughout the Pacific. Meanwhile, it successfully employed a complementary fleet-in-being strategy that sought to harass further Japanese expansion into the South Pacific, before the U.S. Navy had developed sufficient strength to stringently contest Japanese expansion at the Battle of Midway in June of 1942. Admiral Nimitz commented on the strategy by stating that it was designed “chiefly to employ strong attrition tactics and not, repeat, not, allow our forces to accept such decisive action as would be likely to incur heavy losses in our carriers and cruisers.”
By 1943, the American submarine blockade was taking its toll on the Japanese war effort, having robbed it of 1.8 million tons of cargo and approximately 400 merchant vessels, accounting for roughly 16% of Japan’s total tonnage that year. By this time Japan organized its first convoy escort group, the Grand Escort Fleet, starting with only 30 vessels that had been recently constructed, while this figure increased to approximately 150 escort vessels, they were wholly inadequate to defend against American submarines and aircraft.
Meanwhile, Allied power projections resulted in victories at Midway and the Naval Battle of Guadalcanal, as well as Allied expeditionary operations slicing or “island hopping” through the middle of the Pacific toward the Marshall and Mariana Islands. Allied success in logistical battles such as November 1942’s Tassafaronga and the March 1943 Battle of the Bismarck Sea—which General MacArthur called “one of the most complete and annihilating combats of all time”, told the story of the Allied ability to deny sea control to Japan.
By 1944, Japan’s independently operating combat arms were run down. Its navy and air wings had been thoroughly exhausted at the June 1944 Battle of the Philippine Sea and the October 1944 Battle of Leyte Gulf. Its imports had fallen from 48 million tons in 1941 to a paltry 17 million tons in 1944. The fall of 1944 attacks on Formosa virtually annihilated any remaining Japanese aircraft outfitted for submarine hunting. At Iwo Jima in March of 1945, American landings were unopposed, with Japan’s maritime communications effectively disabled, 23,000 Japanese troops occupying the island were sacrificed. Some 120,000 Japanese soldiers were lost on Okinawa shortly thereafter, despite the attempts of the Japanese Imperial Navy’s remnants to save them, which was no match for the U.S. Fifth Fleet, which had by now amassed 40 carriers and 18 battleships among a plethora of other vessels. Japan’s fate was sealed; its merchant marine was now only 12% of its prewar size, no longer capable of maintaining such a widespread empire.
Japan’s actions in the Pacific with regards to attacking American and Allied maritime communications are curious. They did not employ any of the strategies or tactics that the Allies had successfully implemented in the Atlantic to combat the same threats. Japanese forces did try to disrupt Allied air bases, but did not truly throw their forces into a “guerilla” effort until their battle fleet had been virtually annihilated, coming too late to prolong the war.
In conclusion, the battle for maritime communications between the Allies and Axis powers was beyond pivotal. All of the Axis powers failed due to simple concepts established in prior wars. They failed to develop integrated and flexible navies, which forced them to rely on often uncooperative military branches for support. Perhaps most fatal of all, they misjudged their relative naval positions and even when their positions became apparent, they refused to adapt their strategy to fully embrace the actions required of an inferior naval force.