By the end of World War II, Allied naval forces were attacking Adolf Hitler's U-boats long before they could reach convoys. Sixty years later, antisubmarine warfare has reverted to the defensive tactics of the past. Bringing the fight to potential future enemies means attacking subs such as this Chinese Song-class boat where they are most vulnerable—at pierside—before they ever get to sea.
Since late in World War I, most naval officers and analysts have viewed antisubmarine warfare as a defensive operation. Various offensives against German U-boats were tried in both world wars but generally were ineffective. The convoy system, adopted in May 1917 after many losses and also employed throughout World War II, became the model for the mission. In World War I and through most of World War II, the technologies and resources that could be brought to bear against submarines made defending targets more effective than attacking the aggressors. By the end of 1944, however, offensive tactics were achieving far more contacts and sinkings than convoy escorts. Interdiction of the approaches to France through the Bay of Biscay by radarequipped maritime patrol aircraft made that passage a difficult and dangerous one for U-boats. German attempts to defend against this threat with antiaircraft weapons were fruitless, and the snorkel came too late to conceal transits through areas controlled by Allied aircraft. At the same time, on the open ocean, the Germans' radio communications allowed the combination of direction finders and code breakers to furnish the intelligence needed to dispatch offensive antisubmarine forces (hunter-killer groups) to their targets. In both of these scenarios, the hunters became the hunted. By 1945, German losses were staggering-only one boat in five returned from patrol.
In spite of these successes, and of the offensive antisubmarine tactics developed late in the Cold War, the high-value-target or convoy-protection model remains the main approach to the submarine problem in the minds of most naval officers. Arguments supporting the need for many small antisubmarine ships (the escorts) and long-legged antisubmarine assets to accompany aircraft carrier and expeditionary strike groups arise from this view. But antisubmarine assets with more speed and stamina than the surface groups' are wasted in attempts to sanitize the vicinity of high-value targets. Such platforms, if able to operate independently, could be employed much more productively in offensive operations aimed at undersea control throughout the theater, not just the few hundred miles around the convoy, the transit lanes, or a sea base.
Several factors make convoy protection a faulty model for modern operations against submarines. First, the number and relative capabilities of potential enemy submarines is lower than at any time since 1914. Second, the value of today's individual targets is high, but they are fewer, faster, and much more difficult to find and hit than those 8-knot, 100-ship Halifax-to-Liverpool convoys of 1943. Third, because submarines now can lay well off their target's track to launch missiles (though not torpedoes) from any azimuth, the area that must be defended in the protection model today is vastly greater than when submarines had to get close to their targets. Protecting a large and constantly shifting area is complicated by the limitations even moderate speeds impose on the effectiveness of active sonars and trailing antennae. Fourth, the United States possesses an asymmetric advantage in capabilities and operational experience: if U.S. forces are deployed early and employed offensively, they can be positioned to thwart or kill any submarines that might threaten control of the sea.
Today, the numbers of submarines the United States is likely to face in any probable crisis are small and made up almost entirely of diesel-electric boats of limited endurance, low firepower, and negligible agility. Few operate regularly or in realistic exercises. Each one could be a formidable threat if operated skillfully, but submarining is not a casual skill like suicide bombing, when requires only courage. As the Chinese have learned recently, when undertaken by the ignorant or unpracticed, submarines kill crews rather than enemies.1 This balance of forces will not last forever, but it is likely to hold true for the immediate future.
Current intelligence from reconnaissance, intercept, and long-range sensors is as vital to offensive antisubmarine operations as warships and aircraft, but an antisubmarine campaign does not begin on day one of the battle or when the fleet approaches enemy shores. Gathering intelligence (e.g., determining potential enemy dispositions, equipment, tactics, and movements) is an essential precursor for an effective antisubmarine campaign. Much of this can come from space-based sensors and electronic surveillance aircraft, but there are additional measurements to be made. The character of the ocean in the expected area of conflict is vital: the sound velocity profiles, the effect of fresh water, the diurnal variations, the character of the bottom, the most likely locations for mines, the probable channels for dispersion, and similar information. These are not measurements that can be determined by a glance at the chart. This preparation of the battlefield involves actions months or even years before a conflict takes place.
The optimum tactic is to attack submarines while they are moored. The principal obstacle to this comes from the political reluctance to begin a conflict without overt action by the enemy. The recent preemptive U.S. attack on Iraq set a precedent. But that has eroded substantially, and political reluctance remains. Even in that conflict, permission to attack mine layers before they could get under way to lay their mines never came, in spite of Admiral Stan Arthur's admonitions of that important lesson from the previous Gulf War. Regardless of the likelihood of its political acceptance, the relevant commander should press for permission and be prepared to execute the tactic if given the word to do so.
If attacking the enemy in home ports is not allowed, tackling the opponent's submarines as they deploy is the next best tactic. If shooting is not permitted, then escorting the enemy submarines from their diving points to their operating areas certainly is feasible. This requires antisubmarine forces with long endurance to be present when enemy submarines sortie. In the case of a dieselelectric submarine, the presence of an escorting maritime patrol aircraft or nuclear-powered submarine probably will not be detected. If political authorities can be convinced to declare such sorties to be threatening before open war starts—as President Franklin Roosevelt did in 1940 to U-boats west of Iceland—then such transits by potential enemies can be ended before they reach their initial diving points.
In these circumstances, the word "escort" gets a new meaning: a platform accompanying the target submarine. The escort can emphasize the vulnerability of the escorted vessel openly or randomly by noncovert activities such as an occasional radar or active sonar emission. The unnerving effect of such an action may not cause the potential enemy to defect, but it will certainly concentrate the mind on survival, not attack. Should the conventionally powered submarine shut down and go quiet as a result of such moves, she has effectively anchored herself in a spot from which she can move only at a snail's pace, where battery capacity will be used quickly, and where stealthiness can be maintained only as long as the boat's captain is willing to forgo aggressive action.
These sorts of tactics are possible because submarines operate in ones and twos-not in dozens or fleets. Spacebased sensors allow submarines in port and under way to be counted. The result of this intelligence—the numbers of enemy submarines under way—lays the basis for deployment of forces to intercept, locate, and track them. Past performance has shown that such tracking can be accomplished covertly, even when the target submarine is a relatively fast nuclear-powered submarine.
In the situation where shooting is not allowed and sufficient numbers of aircraft and submarines have not been deployed in enough time to permit a one-to-one ratio of pursued and pursuer, the trade-off between following and searching becomes a theaterwide command issue, not a local one. Not every enemy submarine needs to be trailed. Making the choices depends not only on the capabilities of the pursued and pursuer, but also on what other forces are or will be available and what other tasks portend. Only a theaterwide view can evaluate these.
Even if all enemy submarines cannot be followed or killed, early detection reduces the antisubmarine problem markedly. Any locating data helps build the relevant operational picture, facilitating maneuvers to avoid known submarine areas or to concentrate antisubmarine forces. When shooting is allowed, prosecution until elimination must be the goal. In an antisubmarine campaign, every submarine not in overhaul and all the maritime patrol aircraft that can be jammed into the available fields need to be mustered for the fight. Every ocean surveillance ship should be directed to the scene of action, and all the long antennae antisubmarine ships should be brought into the campaign as soon as air superiority is established.
In the event deployments have not been forehanded and enemy submarines have left their home ports for the open ocean, the antisubmarine problem turns into a tedious search exercise-but not an unbounded one. Once we know which submarines might be at sea, the geography involved, and the availability and capability of various search sensors, computer analysis can develop efficient search patterns. Mobilizing this information transforms the search from random seeking of potential intruders to planned measures that narrow the locations of probable contacts. Such tools make offensive antisubmarine warfare more efficient, as well as more effective, than waiting for a flaming datum. They also establish locales that can serve as sanctuaries for sea bases. Even with these tactics, however, if the enemy is allowed to deploy without detection or opposition, the resulting fray will be measured in weeks.
The technologies available for wide-area search above and under the seas are vastly better than in the past. Spacebased, relocatable bottom-mounted, and wide-area search sensors connected by long-range communications exist. When unmanned undersea vehicles become available as search devices, the search rate for their mother ships will increase vastly. The command-and-control network for conducting theaterwide offensive antisubmarine warfare was proved 20 years ago. Concentrating forces, extending searches to the most likely areas of contact, reducing attention to areas of no interest, and routing ships around areas where diesel-electric submarines have been observed all can be accomplished easily from a theaterwide vantage. Tactical command in an antisubmarine attack always is in the hands of the on-scene commander, but central direction is needed to coordinate forces earlier and over much wider areas than those controlled by strike groups.
The contributions of maritime patrol aircraft in this design are vital but have some limits. The success of these aircraft in the Cold War depended on cueing from otherssonobuoy inventories limited their utility as search vehicles. The requirement for an airfield limits deployment in some areas, and in those cases where antisubmarine warfare must be conducted in waters close to an enemy shoreline, the required mastery of the air could be problematic. The ability of patrol aircraft to arrive on station and to localize after detection in the open ocean, however, is the best of any antisubmarine vehicle, and their capacity to maintain contact after localization usually is very good. Radar flooding of an area by an aircraft, manned or unmanned, is important to discourage a diesel-electric submarine from trying to reposition on or near the surface.
The key ingredient in any antisubmarine action is time. This includes the time needed to get forces on station before enemy ships get under way. Because few navies have experience in deploying quickly or for extended periods, this may be more achievable than it appears at first glance. Few navies other than the U.S. and British have experience getting submarines to sea rapidly or keeping them there for more than a few weeks. Diesel-electric submarines, if sent to sea too soon, risk expending their food and fuel before a conflict begins. When ordered to go from a standing start, unpracticecl crews take a great deal of time to get under way for war.
Having U.S. antisubmarine assets deployed forward, operating under the authority of a theater command dedicated to ensuring access rather than under a task group commander handcuffed to a force movement and dependent on a long logistics line makes them an offensive arm even before hostilities commence. Forward presence is more important in antisubmarine warfare than in any other facet of war. The ability to deploy fast is great, but being there before a conflict begins is even better. This requires long legs in each antisubmarine platform, enough platforms to maintain presence in areas of interest and concern, and enough wide-area sensors to buttress them in the initial locating period. Maritime patrol aircraft can play a part in these activities, particularly with dieselelectric submarines that have gone stealthy in some spot. Surface ships have a role where there are no air threats and only low speeds are required. The offensive described here, however, can be executed best by submarines.
These are not the tactics of traditional escort-focused antisubmarine warfare, nor do destroyer sailors or helicopter pilots practice these techniques. The command-and-control processes for this type of campaign are more related to strategic bombing than to historic maritime sea control. Modern sensors and communications allow this type of campaign to be centrally directed and coordinated with a minimum of communications while promoting the tactical initiative of the individual on-scene commanders. The precedent here is not Jutland or Midway, but the Japanese offensive against Port Arthur in 1905. There, torpedo boats and mines took Russia's Asian Fleet off the board in the first actions of the war.
What are the immediate effects of this analysis? The dispatch of antisubmarine platforms, particularly submarines, as part of a strike group relies on bad tactics, downplays our tactical expertise, and fails to take advantage of our asymmetric capabilities. Submarines, patrol aircraft and their supporting arms, ocean surveillance and intelligence assets, sensors, and analysts all belong forward, operating in the areas of likely enemy submarine operations. The inclination to consider submarines as strike vehicles because they bring a substantial portion of the missiles to the scene of combat warps the view of the commanders who employ this unique weapon system. Even though strike is a mission to which they bring short time of flight, prolonged endurance, and stealthy presence, if enemy submarines might be near, it is secondary. Other platforms are available to deliver strike weapons, but only submarines can engage in antisubmarine warfare before command of the air is established.
When highly mobile pursuers with unlimited endurance are aimed against submarines of limited mobility with scarce intelligence, antisubmarine warfare changes from a vast open-ocean search problem to a timed operation governed by the cyclic requirements for the battery-powered submarine to charge.2 The freedom of action gained by sinking minelayers before they can sow their weapons and by knowing enemy submarines at sea are eliminated, pinned down, or precisely located is incalculable. In this situation, a sea base becomes secure: carriers can operate freely; surface warships can focus on antiair warfare and strike; submarines not engaged in antisubmarine operations can be stationed forward with their missiles ready to engage targets; and amphibious assault ships can proceed to the most advantageous positions.
This concept of operations cannot be simply the subject of essay, conjecture, or even war plans. Antisubmarine warfare is a team game and needs to be practiced-in war games as well as in operations and exercises. Not only must the Navy have experience in its own house and on joint staffs, but there also must be a foundation of understanding in policy makers at the highest levels of the Pentagon and the National security Council. Such understanding can be gained only by involving these policy makers and associated joint staff personnel in the games and exercises that demonstrate the benefits of early action, as well as by familiarizing them with the time lines involved with various component parts. If a decision maker understands that failure to allow an attack on an opponent's submarines means a long delay in any further action to close with an enemy's territories, he or she may be more inclined to give a sympathetic ear to the suggestion to shoot them at the sea buoy.
Forehanded, aggressive, persistent attack against enemy submarines, bringing all assets available to bear, is the characteristic of offensive warfare in this as in any medium. This was the essence of the Maritime Strategy and meets the admonition of Alfred Thayer Mahan: "War, once declared, must be waged offensively, aggressively."3
1 "Submarine Sinking Kills Seventy," BBC News World Edition, 5 May 2003.
2 A nominal cycle for charging the batteries on a diesel-electric submarine would be 4 to 8 hours out of 24 to support a movement at 3 to 8 knots for 12 to 20 hours.
3 Alfred Thayer Mahan, "The Interest of America in Sea Power," quoted in Col. Robert Debs Heinl Jr., USMC (Ret.), Dictionary of Military and Naval Quotations (Annapolis, MD: United States Naval Institute, 1966), p. 220.
Admiral Holland served primarily in submarines. He participated in early combined arms antisubmarine warfare operations.