Sinking Ships

July 1, 2006

Two days after Pearl Harbor, Japanese land-based bombers and torpedo airplanes sank the British battleship HMS Prince of Wales and the battle cruiser HMS Repulse north of Singapore in the South China Sea.

Eight hundred and forty sailors died, but the loss of life is not what shocked the naval world. The battle marked the first time in history that capital ships were sunk by air attack while operating on the high seas.

The efficacy of airpower against naval forces had already been demonstrated at Pearl Harbor and, more than a year before that, in the British attack on the Italian fleet at Taranto, but both of those engagements were against fleets that were sitting in port.

Naval convention was sometimes difficult to overcome. Off the Malay Peninsula on Dec. 9, 1941, Adm. Thomas S.V. Phillips, British force commander, believed so strongly in battleship superiority that he made no effort to arrange for air cover, even while under attack. He was among those killed in the sinking of Prince of Wales and Repulse.

Ironically, Phillips had once counseled a junior officer that aviation was “poppycock” and steered the officer away from the aviation profession because it would “ruin” his career.

By the end of the war, Japan was defeated, in large part, by the same maritime interdiction strategy it had helped validate. Land-based airpower helped destroy Japan’s maritime capabilities, paralyze the Japanese war machine, and strangle its industries and economy.

As an island nation lacking strategic resources, Japan needed to import raw materials and energy to fuel its economy and sustain its military power. In 1937, Japan imported 82 percent of its oil via sea-lanes criss-crossing the Southwest Pacific.

Although the atomic bomb delivered the coup de grace, it was the war against transportation that sealed Japan’s fate in World War II. Contrary to conventional wisdom, it was land-based airpower—not carrier-based aircraft—that proved most effective in the maritime interdiction mission.

Divergent Approaches

Halfway across the world, Britain also was dependent on shipping to support its wartime operations.

“The old dispute about whether the airplane could or could not sink a battleship has long since been answered, but the issue was always somewhat beside the point,” observed Bernard Brodie, author of A Layman’s Guide to Naval Strategy, in 1942. “Discerning observers asked not so much how well the warship would fare under air attack as whether Britain’s vast shipping could be carried on in the shadow of the Luftwaffe.”

The Luftwaffe did not emphasize maritime interdiction, but, after a slow start, the Allies did. The Army Air Forces was woefully unprepared to conduct maritime interdiction missions in the first nine months of the war and initially proved almost totally inept against Japanese shipping.

It took vision to improve the AAF’s initially weak maritime performance. Fortunately for the US and its Allies, Gen. George C. Kenney, Gen. Douglas MacArthur’s top airman in the Southwest Pacific, embraced the maritime interdiction mission. (See “The Genius of George Kenney,” April 2002, p. 66.) Kenney set about improving training and pushed for tactical and technical innovations such as “skip bombing,” low altitude ingresses, and addition of forward firing machine guns.

The US Strategic Bombing Survey, performed by a team of civilian analysts and military officers commissioned by President Franklin D. Roosevelt to investigate the effects of bombing, concluded, “The war against shipping was perhaps the most decisive single factor in the collapse of the Japanese economy and the logistic support of Japanese military and naval power.”

The Quiet Force Multiplier

Airpower played a low profile but critical role as a force multiplier in the Pacific campaign. Submarines never were available in sufficient numbers to enforce a blockade of Japan on their own and, consequently, depended on land-based airpower to supplement their search patterns.

“The development of effective cooperation between the submarines and the air arm permitted the results of continual air patrol and search to be translated into effective submarine attack, where such attack was the most appropriate method to employ,” stated the strategic bombing survey. “It must be understood, however, that particularly as the sea-lanes contracted and more effective escort was supplied, the task of the submarine became hazardous and losses were considerable.”

Unlike the submarine experience, land-based airpower’s effectiveness improved as shipping lanes converged, especially when ships were funneled into natural choke points.

Aerial attacks began to exact a dreadful price on Japanese ships, even as they hugged the coasts in desperate attempts to escape the deadly effects of Allied airpower. Enemy ships became sitting ducks, and when bombers found concentrations of ships, the attacks were lethal.

In the March 1943 Battle of the Bismarck Sea, more than 100 Allied aircraft swarmed and destroyed an entire Japanese convoy. Japan lost some 3,500 troops. Only about 800 of the 6,900 soldiers who were being ferried to reinforce critical areas made it to their destination. The defeat there was “unbelievable,” remarked a Japanese destroyer captain. “Never was there such a debacle.” (See “Victory in the Bismarck Sea,” August 1996, p. 88.)

The Battle of the Bismarck Sea foreshadowed the terrible toll that land-based bombers would exert on shipping. The Japanese high command soon announced that every soldier would be taught to swim.

Carrier-based air attacks were similarly devastating against large concentrations of merchant ships, but these strikes were sporadic and not part of a continuing program to neutralize enemy shipping lanes. The US Strategic Bombing Survey noted, “In general, the responsibilities of carrier air were presumed to lie elsewhere and to relate more directly to naval operations.”

Kenney thought his land-based aircraft were the best tools to support maritime operations, particularly amphibious landings, because carrier-based aircraft had limited fuel, range, loiter time, and payload. Additionally, aircraft carriers had to periodically discontinue flying operations in order to refuel, rearm, and replace lost or damaged aircraft.

“I consider it unwise to rely on carrier units completely,” Kenney told MacArthur. “Carrier-based aircraft do not have staying power and therefore do not have the dependability of land-based aircraft.” Most importantly, Kenney was concerned about the fact that aircraft carriers could be sunk.

Naval Vulnerability

Kenney’s concern about aircraft carrier vulnerability and fleet limitations proved remarkably prescient. American carriers experienced severe operating challenges during several campaigns and often were unable to protect their accompanying surface fleets.

Under increasing assault from the air, warships needed more capacity to absorb punishment became an ever-more important characteristic of wartime vessels. Shortly after the war, the Bureau of Ships applied engineering principles to estimate the number of hits required to sink each naval vessel and concluded aircraft carriers were the most vulnerable class of combat ship.

The benefits of aircraft carriers, which provide on-call airpower without a need for nearby land bases, are well-known, but the limitations of naval aviation are less frequently discussed. Rear Adm. Daniel V. Gallery, assistant chief of naval operations, summed up an inherent design weakness of the aircraft carrier in a 1949 Science Illustrated article. “A big carrier is a tank farm, an ammunition dump, and an airfield all rolled up into one tight package,” Gallery wrote. “This is a highly inflammable combination.”

An aircraft carrier is a floating city concentrated into four-and-a-half acres. It represents a huge investment in terms of money, materials, skilled manpower, and time. A carrier also is a valuable target for the enemy because of its mobile combat capability. Consequently, the Japanese naval forces made the destruction of US aircraft carriers their top priority.

Those aircraft carriers that were fortunate to survive the Japanese onslaught were out of action for repairs an average of 30 percent of the time during the last year of the war. This further increased the relative importance of land-based airpower, and a series of battles illustrate the critical role played by land-based aircraft.

First, according to the (since declassified) Secret Information Bulletin No. 2, carrier forces were withdrawn during the Guadalcanal landing of Aug. 7, 1942 because of decreased carrier fighter strength, low fuel, and a large number of enemy torpedo and bombing airplanes in the vicinity. During the campaign, Guadalcanal’s Henderson Field remained the key staging location for land-based aircraft, despite repeated Japanese attempts to knock it out of service.

Later, during the 1944 Battle of Leyte Gulf, Rear Adm. Jesse B. Oldendorf cabled an urgent plea for air support to Kenney and the Thirteenth Air Force commander, among others. His cable was indicative of the problems US naval forces were still having in dealing with attacking enemy aircraft.

Oldendorf relayed, “Naval forces covering Leyte report two heavy air attacks today. One destroyer has been sunk by torpedo planes. Three additional severely damaged. If adequate fighter cover not maintained over combatant ships, their destruction is inevitable. Can you provide necessary protection?”

Finally, during the spring 1945 Okinawa campaign, US Navy ships were required to operate within range of Japanese land-based aircraft. For that campaign, the Navy had 15 carriers in service, with 919 aircraft onboard, but the flattops proved unable to protect the fleet from the Japanese.

Under the assault from Japan’s land-based aircraft, the losses were severe—28 US ships sunk and 225 damaged.

A postwar analysis of the Navy’s Pacific Theater experience revealed carrier airplanes averaged only one flight every other day while in a combat area. Of those sorties, at least a quarter were normally assigned to the defense of the naval task force—the burden of defending carriers severely limited the offensive airpower provided by carriers and the sorties available for maritime interdiction.

Army Air Forces units, meanwhile, generated unmatched sortie rates and firepower. For example, in one three-day span, 167 B-29s operating from the Mariana Islands delivered 2.5 times the bomb load that 1,091 carrier aircraft did over the same days.

Aircraft carriers also must operate according to strict launch cycles and cannot remain on station indefinitely. Carriers can surge to temporarily generate additional sorties, but must eventually stand down.

In contrast, the facilities at a land-based airfield are dispersed over an area of several square miles, are frequently open to further expansion and enlargement, are cost-effectively constructed of ordinary building materials, and are available for use 365 days of the year as they never have to return to port or refuel.

An Unwanted Mission

Land-based airpower would have sunk even more ships if not for interservice politics that hindered unity of effort. The Army and Navy bickered over who should control bombers engaged in sea duty.

Neither service, though, was particularly interested in a more robust use of bombers to attack Japanese shipping and, consequently, did not take full advantage of land-based airpower’s maritime interdiction capabilities. Post-war analysis suggests a more concentrated effort against enemy shipping, especially oil tankers, could have accelerated Japan’s decline.

Adm. Ernest J. King, the Chief of Naval Operations, primarily wanted to use bombers to supplement fleet defense, whereas Gen. Henry H. “Hap” Arnold, the Chief of Army Air Forces, was less than enthusiastic about assuming maritime duties at the expense of the strategic bombing mission.

King advocated a plan to assign control of the bombers to Navy commanders in specified sea frontiers. This would have divided operational control, which ran counter to AAF doctrine. King was suspicious of any plan that would bolster calls for air force independence and potentially steal the Navy’s air component.

Conversely, Arnold was suspicious that King’s proposal, if approved, might be the “forerunner of the Navy assuming the Army’s primary responsibilities and functions for operation and control” of a land-based air force.

The Army and Navy negotiated the Arnold-McNarney-McCain agreement, which divided responsibility for the employment of long-range aircraft. “In return for unquestioned control of all forces employed in protection of shipping, reconnaissance, and offshore patrol,” the Navy relinquished control of long-range striking forces operating from shore bases.

The Army transferred its antisubmarine B-24s to the Navy. The agreement was designed to prevent each service from encroaching on the other’s historic responsibilities.

Gen. George C. Marshall, Army Chief of Staff, expressed dismay over the two services’ inability to work together and disapproved of policies that artificially divided the maritime medium. He thought the Army and Navy procedures were “neither economical nor highly efficient and would inevitably meet with public condemnation were all the facts known.”

The limited cooperation between the Army and Navy air arms was offset by the enmity between Japanese air arms, which far surpassed the American interservice rivalry. The Imperial Japanese Army Air Force did not help its naval counterparts to control shipping lanes.

Expressing discontent, Capt. Minoru Genda, a planner of the Pearl Harbor attack and commander of an elite squadron of pilots, commented, “The Army fliers didn’t like to fly over the ocean” and “acted as though they didn’t realize the importance of the control of the seas.”

Lessons Relearned

The utility of land-based airpower against maritime forces has been repeatedly demonstrated in more recent events. In the brief 1982 war with Argentina over the Falkland Islands, Britain almost suffered a fate similar to its Dec. 9, 1941 experience.

During the Falklands campaign, Argentina only had four French-built Super Etendard fighters capable of employing Exocet antiship missiles. Despite the small size of the threat, British task force defenders were unable to stop these aircraft from sinking the destroyer HMS Sheffield and a supply ship.

Other Argentine aircraft, carrying less advanced weapons, also found their mark. In the South Atlantic waters around the Falklands, 75 percent of the British task force was damaged or sunk. The carnage could have been far worse for the British forces: At least 14 Argentine bombs hit their targets but failed to detonate.

Aircraft carriers may no longer be the most effective way to exert control over the world’s oceans. Long-range aircraft can operate worldwide, reducing the need for forward bases.

Allied Air Attack Damage—By the Numbers

Carrier-based aircraft in World War II were responsible for sinking the greatest proportion of Japan’s combat fleet, including five battleships and 10 enemy aircraft carriers. It was land-based airpower, however, that was most effective against Japanese merchant shipping.

Land-based aircraft (through direct action and mines) sunk approximately 23 percent of the total enemy merchant ship tonnage sent to the bottom of the Pacific. Carrier-based aviation accounted for approximately 16 percent.

Yet these figures underestimate the contribution of land-based aircraft to the maritime fight. Land-based airpower also destroyed large numbers of barges and small vessels—of less than 500 tons gross weight—not counted in the totals. (Sea-based aircraft destroyed relatively few small ships because they spent little time patrolling the coastal waters and harbors.)

The Army Air Forces attacks compare favorably to the efforts of the other services—the AAF devoted less effort but dropped more bombs and sank a greater number of ships than the other services.

AAF’s Pacific forces flew 7,250 (1.5 percent) of their sorties to maritime interdiction and sank 265,360 tons of enemy shipping. In comparison, Navy and Marine Corps aircraft flew 25,657 (9.9 percent) of their sorties against merchant shipping and sank 102,702 total tons.

The AAF sank 2.5 times the enemy tonnage with less than a third of the sorties devoted to the mission.

The disparity in relative effectiveness is magnified when you include Twentieth Air Force’s mine-laying campaign. Twentieth flew 28,826 sorties and delivered 9,875 tons of mines, which sank 287 enemy ships and damaged 323 others.

After April 1945, mines dropped by B-29s in Japanese harbors and inland waterways accounted for half of all enemy ships sunk or damaged.

This aerial mining crippled Japanese merchant shipping, denied damaged ships access to repair facilities, closed strategic waterways, and threw the administration of Japanese shipping into hopeless confusion.

There are limits to what constitutes acceptable risk as well. Losing a single aircraft is bad enough, but, security affairs writer Robert Kaplan has warned, “The effect of a single Chinese cruise missile’s hitting a US carrier, even if it did not sink the ship, would be politically and psychologically catastrophic.”

“The capability for airmen to rapidly respond anywhere in the Pacific to sink naval vessels in all weather, day or night, is crucial,” noted Gen. Paul V. Hester, commander of Pacific Air Forces. In 2004, he and Lt. Gen. David A. Deptula, PACAF vice commander, recognized that the Air Force’s ability to contribute to the maritime fight had atrophied and sought to reinvigorate PACAF’s maritime capabilities.

Consequently, the November 2004 Resultant Fury exercise demonstrated the ability of fighters and bombers to hit and sink moving ships, with precision weapons, in all weather conditions.

The exercise showcased prototype technology. Strike aircraft coupled the GPS-guided Joint Direct Attack Munition with the developmental Affordable Moving Surface Target Engagement system.

Air Force and Navy forces worked together to destroy multiple mobile seaborne targets, including a decommissioned tank landing ship, USS Schenectady. Tracked on the move by E-8 Joint STARS aircraft, the targets off Hawaii came under fire from B-1 and B-52 bombers flying nonstop from Andersen AFB, Guam, and Dyess AFB, Tex., among other aircraft.

Resultant Fury was judged a resounding success, demonstrating that Air Force aircraft can sink moving targets. AMSTE is still a developmental system, however, so the exercise did not reflect current operational capabilities.

The fact that land-based airpower is effective against active shipping and naval forces is well-understood today. During World War II, however, this was a new concept that achieved spectacular results against Japan once anti-shipping efforts were a priority.

Air Force Maj. Lawrence J. Spinetta is an F-15 instructor pilot and former international affairs fellow at the Council on Foreign Relations. This is his first article for Air Force Magazine.