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Executive Summary

This paper is reflective of the content of Naval Postgraduate School course, Undersea Warfare: Yesterday, Today & Tomor- row. Specifically, a force and counterforce concept is examined which frames how the diversely different inventions of the submarine and aircraft evolved over time, each bearing some influence on the other. History demonstrates that the development of new weapon technology closely follows operational require- ments. This may be due to apprehension of impending vulnerabil- ity as shown in the case of British Admiralty calling for ideas to use aircraft against submarines in the years just prior to World War I. It may also be in direct response to an ongoing crisis, demonstrated in the implementation of the Tenth Fleet for the purpose of countering the U·boat threat and protecting Allied merchant shipping during World War II. The unforgiving laboratory of warfare accelerates the pace of such development, expending human lives, expertise and national treasure in order to gain an advantage. The art of anti·submarine warfare reached a pinnacle during the Cold War when air, surface and subsurface platfonns integrated efforts, capitalizing on available intelligence.

Twentieth century warfare illustrated how new technology can transform the way in which warfare is conducted, challenging traditional doctrine. The continuous pressure to obtain an advantage drives the technology in ways that might not be duplicated in times of peace. The twenty-first century will likely bear the continuation of this axiom as growing nations invest in submarines to protect their interests in the maritime domain. Maritime assets, both manned and unmanned must work closely together to counter the inherent advantages of modem submarines. The U.S. is wise to continue its investment in Undersea Warfare so that it can maintain or in some cases regain advantage in the anti-submarine warfare arena. Losing advantage in the undersea domain is a very heavy price to pay.


The twentieth century brought rapid change in the realm of maritime warfare. 1 Technology reached a point at which it began to produce machines that fulfilled the visions of earlier creative thinkers and engineers. Dreams in which humans traversed the sky as well as under the sea became reality thanks to engineering feats of the day. As early as 1912, the British Admiralty sought ideas to counter the emerging threat of submarines. A uniquely qualified British submarine officer named Hugh Williamson (who also learned to fly aircraft at his own expense) responded with an innovative and perceptive paper. In addition to the description of a well-suited aircraft and crew, Lieutenant Williamson intuitively described a means of neutralizing submarines so groundbreaking that it would be used during both World Wars of the coming century. 2 He described how an aircraft could prevent a subma- rine’s access to the surface by forcing it to submerge. He even described rudimentary means in which an aircraft might attack a submerging boat with bombs. His concept of an anti-submarine weapon and description of timed fusing for specifically designed bombs proved to be a revolutionary concept and demonstrated exceptional forward thinking even in an age of rapid technological advancements. 3 Jn addition to written appreciation from the Admiralty, Lieutenant Williamson qualified in both the submarine and aviation branches of the Royal Navy.’

The onslaught of World War I in late 1914 thrust these techno- logical advances forward, challenging traditional naval doctrine. 5 Maritime platforms, including aircraft rapidly advanced as weaponry, reliability and range continuously improved under the relentless pressure of armed conflict. Differences among submarine, surface, and airborne platforms are quite apparent. The submarine relies upon stealth to offset its relatively low speed in the hunt for targets. As the primary target of submarines, surface ships had little advantage and urgently sought an adequate countermeasure to the emerging threat. Meanwhile, aviators sought ways to exploit speed and the vantage point of altitude to compensate for noisiness and lack of stealth. The remainder of the twentieth century saw the evolution of the naval platforms through two World Wars as well as the Cold War with the former Soviet Union. Throughout the twentieth century, submarine platforms became an ever more formidable naval force and significantly impacted naval doctrine. Surface ship and aviation platforms diligently strove to develop countermeasures, leveraging science and technology to offset the threat brought by modem submarines. Need drives military technology; future advancements in Undersea Warfare are likely to support this axiom.


In mid-1914, the navies of Britain, Germany, France, Russia, Austria-Hungary, Italy, and the United States all possessed submarines. The fact that future participants in World War I operated submarines made their expansion as a maritime weapon inevitable. As observed in Admiral Alfred Thayer Mahan’s writings, “The submarine possesses in high degree the power to strike a blow deadly as the rattlesnake or cobra, and of as little waming.” 6 This threat could not be ignored. Anticipating the expansion of submarine usage in maritime conflict, the U.S. Navy broadened its investment in long-range submarines and awarded a contract to build two ships to the Electric Boat Company in 1914. 7 Assistant Secretary of the Navy and future U.S. Commander in Chief, Franklin D. Roosevelt stated that the submarine had “taken its place not as the sole weapon in naval offense and defense, but as an adjunct to other weapons.” 8 This decision greatly impacted U.S. maritime development and doctrine and continues to resonate to this day.

The sea confrontations of World War I quickly proved that submarines significantly impact the balance of maritime power. Shortly after the onset of hostilities, a German U-boat sank the light cruiser HMS PA TH FINDER in the first event of a submarine sinking a surface ship since the American Civil War. 9 In the following weeks, both German and British submarines met success against enemy surface warships. To underscore the impact of submarines further, the German Kaiser gambled and authorized unrestricted U-boat warfare in early 1917, blurring the line between traditional combatants and non-combatants. 10 The decision created a devastating impact to the island nation and caused the loss of about 6 million tons of British shipping in 1917 alone. 11 The grave effect on Great Britain threatened the outcome of the war. These maritime confrontations revealed that traditional naval vessels and defenses had little immediate means to counter the threat brought by submarines. Both British and German submarines took advantage of concealment and stealth inherent in their design. However, German U-boats demonstrated the most significant impact, successfully employing submarines as strategic weapons to choke desperately needed supplies from Great Britain. Meanwhile, the British experienced great difficulty in finding an effective anti-submarine warfare weapon. 12 Seemingly, the entry of the United States to the war in 1917 shifted the outcome to the eventual favor of the Allies despite never completely countering the threat of German submarines. Of course the Armistice of World War l did not close the chapter on German U-boats.

Naturally, the Allies made a concerted effort to counter the success enjoyed by the Germans. The airplane, a more recent invention than the submarine became one of the tools used to offset the inherent advantages of vessels relying on concealment. However, the impact of aircraft as a counterforce was much less immediate, hampered by the challenges of locating and attacking targets that occupied an entirely different physical domain. 13 Although difficult to locate submarines operating in a different domain, the separation did protect aircraft from submarine attack, in contrast with naval and merchant ships not enjoying such advantage. Submarines had the ability to hide themselves under the sea; aircraft transited the skies at relatively high speeds, but unable to peer directly into the depths that concealed the submarine platform. Nonetheless, military officers worked diligently to develop tactics and procedures in a quest to counter the concealed threat from below the sea. The German Zeppelin, L-5 conducted the first-recorded attack by an aircraft upon a submarine when the airship harmlessly dropped two bombs on the ocean surface in an attempt to hit the British submarine, £-11 in December of 1914. However, the first successful kill of an enemy submarine did not occur until September of when aircraft from the Austro Hungarian Naval Air Ann spotted the shape of a submarine, transiting clear waters in the Adriatic Sea. The position contained no known friendly submarines and the flight of two flying boats dropped a total of four bombs upon the target.

Three of the weapons caused significant damage to the French submarine FOUCAULT, damaging her batteries and forcing her to the surface. Determining his position to be hopeless to the presence of attacking aircraft, the French Captain ordered his ship to be abandoned and scuttled her to the bottom. Making the historic talc even more remarkable, the Austrians jettisoned their remaining weapons, set their flying boats upon the calm waters and rescued the French crew without the loss of a single life. 16 This event changed the concept of using aircraft to locate and kill submarines from theory to a demonstrated capability .

As the science of aviation rapidly advanced in the years of World War I, the submarine commanders became aware of the legitimate threat of an air attack. Although aviation assets never sank submarines in great numbers, aircraft presence affected submarine commander behavior. From this perspective, the success of anti-submarine aircraft is better measured by the number of friendly ships saved than by the number of enemy submarines destroyed. 18 Rapid technological developments in aviation such as engine reliability, aircraft range and advances in weaponry further enhanced the capability of the aircraft as an anti- submarine warfare tool. Exploring military uses for such improvement, the Allies developed innovative concepts to defend the newly implemented convoy system in coastal regions. The presence of blimps affected the behavior of U-boats and often posed enough of a threat to clear them from Allied merchant shipping paths. 19 In April of 1917, Oying boats with obviously faster speeds than blimps employed Spider Web patrols which consisted of octagonal-shaped tracks by which aircraft systematically patrolled a four thousand square mile area that straddled the English Channel.

To summarize the concept of force and counterforce during World War I, the submarine used its stealth to gain advantage while aircraft used presence and the persistent threat of lethal attack to counter submarines. The effect of anti-submarine patrol aircraft is generalized by the writing of a British submariner who wrote that “aircraft were an infernal nuisance”. 21 If a submarine spotted an aircraft, the commander assumed the advantage of stealth lost with potential targets well protected. 22 Thus, anti- submarine aircraft prevented enemy submarines from mission accomplishment, just as Lieutenant Williamson recommended in 1912. Aircraft had the advantage of speed and the ability to patrol a large area from the sky, while submarines enjoyed the advantage of stealth. Meanwhile, aircraft still had little means to detect submarines while submerged and relied upon diligence and binoculars to spot submarines operating on the ocean surface.

During World War II, the force, counterforce dynamic be- tween submarines and other maritime platforms continued. The Royal Navy immediately returned to a convoy system for merchant ships from September of 1939 and onward. In response, the Germans implemented the Wolf-pack tactic in which radio- coordinated U-boat attacks might challenge the effectiveness of convoys, requiring a high degree of coordination and High Frequency (HF) communication. Soon after warfare returned to Europe in 1939 the Royal Air Force commenced patrols of the North Sea with orders to attack Gennan U-boats on sight. 23 However, early British air attacks on submarines proved unsuccessful. The aircraft lacked an effective bomb sight to employ against enemy submarines, requiring them to release from a lower altitude to achieve any hope of hitting their target. Bomb shrapnel caused more damage to the attacking aircraft than its target. 24 Military technology languished between World Wars without an operational need for air dropped anti-submarine weapons. Ironically, the usage of Scarecrow aircraft in support of convoys proved just as effective as the armed aircraft in the earliest part of World War II. The Scarecrow patrols mostly sighted and reported submarines, forcing them to submerge and deterring them from their mission. The patrols contributed to the uncertainty felt by the submarine commanders and could only consider effectiveness by the number of ships 1101 sunk by U- boats, although a difficult metric to measure.

Throughout the war, technologies began to develop that would assist aircraft and surface ships in the pursuit to become more effective submarine hunters. Improvements to High Frequency Direction Finding (HFDF) equipment enabled the Allies to geometrically plot bearings and locate the position of U-boats communicating via HF radio transmissions. 25 Control stations vectored fast surface ships or aircraft to intercept and attack the U- boat, thwarting Admiral Doenitz’s Wolf-pack tactic. 26 Advances such as Radio Detection and Ranging (RADAR), sonobuoys, Magnetic Anomaly/Airborne Detection (MAD) and improvement in radio communications developed relatively quickly with the ongoing need to gain an advantage. 27 The British gained an invaluable advantage by capturing code books, cipher documents and a complete German Enigma coding machine from U 110 in 1941. 28 This also assisted the Allies in gaining an upper-hand over the U-boat threat.

As anti-submarine warfare capability developed, it became clear that aircraft demonstrated their greatest effectiveness when operating in cooperation with other maritime assets. Throughout the course of World War II, anti-submarine aircraft significantly improved from a poorly armed daytime nuisance to an effective submarine killer at all times during the day and night. 29 This impressive increase in capability occurred due to massive resources employed as a direct response to the U-boat menace.

The technologies borne in the demanding environment of World War II would prove to be significant tools used by future aircraft throughout the course of the Cold War years. North Atlantic Treaty Organization (NA TO) countries honed anti- submarine skills throughout the Cold War against relatively loud submarines. Anti-submarine warfare proved most effective when approached beyond the perspective of individual components or platforms.II Net effectiveness depended on how well individual components and platforms worked together as a system. In the l 980’s integration of anti-submarine warfare effort among surface, submarine, aircraft and intelligence entities developed the ability to locate and track Soviet submarines into an art form. The U.S. and NA TO reached a relative pinnacle of anti-submarine warfare though the integration of effort. Application of maximum strain and uncertainty on an exposed adversary constituted the most effective anti-submarine campaign.

However, this advantage significantly eroded due to the espionage activities of John A. Walker.J 3 According to former Secretary of Defense Casper Weinberger, Walker’s espionage provided Moscow “access to weapons and sensor data and naval tactics, terrorist threats, and surface, submarine, and airborne training, readiness and tactics.” As a result, the integrated anti-submarine campaign suffered. Fortunately, despite the damage done by treasonous activity, the U.S. prevailed in the Cold War.

After the collapse of the Soviet Union, calls to cut military spending and produce a peace dividend negatively impacted the effectiveness of air anti-submarine warfare. The direct threat of adversary submarines to the United States abruptly came to an end. Subsequent reductions in defense spending did not exempt anti-submarine warfare platforms, resulting in reduction in both capacity and capability. This series of events supports the thesis that advances in technology mirror threats, and that the loss of capability was inevitable in the absence of a credible threat from adversary submarines. However, emerging and growing militarizes with significant investment in submarines make the argument seem short sighted.

As the twenty first century advances, the Navy is again emphasizing anti-submarine warfare. Emphasis on integration of anti- submarine warfare leadership and activity is instrumental to success, as demonstrated by the creation of Tenth Fleet in World War II and combined efforts employed during the Cold War. Nowadays, Chinese pursuit of an Anti-Access/Area Denial strategy complicates the operational problem. Additionally, worldwide investment in maritime capability and an expanding submarine force again compel the argument for a counter force. However, the reality of shrinking the U.S. defense budget coupled with exponential increases in platform and weapon costs make the solution particularly difficult. Innovative ideas applying new technology will have to be part of the solution. Concepts employing unmanned aerial, surface and subsurface vehicles will continue to be explored, pushing the art of the possible. The U.S. Navy must strive to be innovative so that it can employ modular platforms such as the P-8 and Littoral Combat Ship (LCS) in order to take full advantage of current and future technical advances. These platforms should evolve with integration of effort with other platforms in mind, striving to place the adversary submarine in a situation that maximizes uncertainty and stress, interrupting its mission. The Navy of today and tomorrow must integrate and innovate in order to provide a legitimate counter force to the expanding numbers of submarines worldwide.


Maritime platforms significantly impacted the face of warfare over the twentieth and twenty-first centuries. Platform technological advances challenged traditional thinking and brought the creation of new strategy and tactics. Submarines continue to take advantage of their inherent concealment and ability to operate covertly. Aircraft leverage their ability to cover large distances quickly and coordinate their efforts with other platforms. Threats and the need to counter those threats will continue to drive technology in the realm of Undersea Warfare. The increasing endurance and persistence of Unmanned Aerial Vehicles (UAVs) and Unmanned Surface Vehicles (USVs) provide another iteration of the long march to counter the threat of manned submarines. The system of systems must develop synergy from manned and unmanned airborne, surface, subsurface and even netted undersea platforms. The need to counter threats and address crisis will continue to drive military technology as demonstrated by history. Budgetary constraints complicate the problem, but offer the opportunity for innovation.

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