The Amphibious Revolution
By
Richard B. Frank
Navy History, August 2005
During World War II, U.S. Forces transformed amphibious warfare from a discredited notion into a key to Allied victory.
At the start of World War II, conventional wisdom ranked horse-cavalry charges well above amphibious landings as an effective means of waging war. Military critic B.H. Liddell Hart declared in 1939: "A landing on a foreign shore in the face of hostile troops has always been one of the most difficult operations of war. It has now become almost impossible. . . . 1 " By 1945, however, the United States had transformed not simply amphibious landings but the very nature of modern warfare.
For Hart and a generation of officers, Great Britain's 1915 Gallipoli disaster had conclusively demonstrated the folly of assault landings. Between the world wars, however, the U.S. Marines were shifting to a new institutional mission of amphibious attack in order to seize advanced bases for the U.S. Navy's anticipated trans-Pacific campaign against Japan, and discerned that the problem was not the concept but the execution. In the 1920s and '30s, the Marines and Navy forged a workable method of modern amphibious assault. The Marines' seminal Tentative Landing Operations Manual emerged in 1935. The Navy adopted it in 1938 as the Landing Operations Doctrine (FTP 167). It became the bible of amphibious landings in World War II and provided the indispensable foundation for everything that followed. 2
The pre-war legacy of amphibious warfare also extended to the most fundamental tools. Prior to the U.S. entry into the conflict, the Navy had converted specialized auxiliaries into what came to be called "combat loaders" or later "attack transports" (APAs). Most were fitted to carry about a battalion of troops and a complement of landing craft to deliver them ashore. Some specialized in hauling heavy equipment, such as artillery (AKAs). 3
The prewar development of landing craft followed a tortuous path—and here the Navy's record sports some blemishes. Translating the Marines' concept of specialized armed and armored landing craft into reality took years of experimentation. Eventually, the 1926 "Eureka" boat design by Andrew Higgins evolved into the immortal Landing Craft, Vehicles and Personnel (LCVP) over fierce opposition from the Navy bureaucracy, which favored its own designs. An enlarged Higgins design to carry tanks became the Landing Craft, Mechanized (LCM). Meanwhile, a 1937 article in Life magazine drew the Marines to inventor Donald Roebling's remarkable amphibious vehicle. Originally intended to rescue aviators in Florida's Everglades, it employed cupped tracks for power both on land and in water. Moreover, it could cross the surf line. Thus, it promised seamless service from ship to inland destinations. The Marines overcame Navy resistance to secure procurement of what was christened the Landing Vehicle, Tracked (LVT) and commonly called the amtrac (amphibious tractor). 4
The Test of War
The first American offensive of the war commenced with daylight landings on Guadalcanal and nearby islands in August 1942. This initial amphibious adventure indelibly taught the lesson followed thereafter in the Pacific theater: The target area must be isolated and local air and sea superiority established. In November 1942, the U.S. Navy and Army mounted landings on the coast of North Africa. The Army demanded quite different operational and tactical techniques because it correctly appreciated that in the Mediterranean and European arenas, Allied forces could never completely isolate the landing area. The Army therefore put a far higher premium on the methods to achieve tactical and operational surprise: night landings, no extensive air or sea bombardment around the invasion site, and little or no preassault naval bombardment by Pacific standards. To its ultimate cost, the Army proved disdainful of Pacific developments. From the soldiers' viewpoint, scale was the key experience, and no Pacific landing prior to late 1944 matched the size of North Africa, Sicily, Salerno, or Anzio. At Normandy, the Army discovered that the key was not the scale of the landings but the scale of the defenses. The initial landings also underscored a handicap that bedeviled all U.S. amphibious assaults during the war: Perfection was virtually impossible because assembling all the air, sea, and land elements and rigorously training them was never feasible. As Samuel Eliot Morison aptly commented, "It was as if a football coach were required to form a team from different parts of the country, brief them with a manual of plays, and, without even lining them up, send them against a championship opponent." 5 The early operations acted as an audit of the prewar doctrine and techniques and ignited a supernova of creative energy that propelled both doctrine and techniques beyond imagining in five areas.
Intelligence and Deception
Amphibious operations usually relied on information from code-breakers and captured documents. For example, intercepts disclosing Japanese intentions to build an airfield on Guadalcanal triggered that campaign and played a key role in selecting targets thereafter. 6 For all of its contributions, however, code-breaking was no panacea. In fact, it inadvertently played a huge role in the heavy losses at Tarawa when intercepts led to the sinking of a Japanese ship carrying a replacement defensive garrison for the main island of less than half the strength of the unit that the Marines would confront. 7 It also failed to identify more than half the defenders at Luzon, Iwo Jima, and Okinawa and missed the first-class German 352nd Division defending Omaha Beach.
The initial landings wanted for tactical intelligence on beaches. Aerial photographs and submarine periscope pictures partly filled this void. The August 1942 Makin Island raid marked a turning point when the designated landing beach proved completely unusable. That convinced the Navy's premier amphibious warrior, Admiral Richmond Kelly Turner, that he needed a specialized unit to survey the subsurface geography from the line of departure to the beach. Underwater Demolition Teams, or "frogmen," met this need and appeared in time for the Marshall Islands operation. 8 Intelligence needs also gave birth to an array of specialized units within both the Army (like the "Alamo Scouts") and the Marines (the Marine Amphibious Reconnaissance Company). 9
Another tool much refined during the war in order to support amphibious warfare was deception. As Thaddeus Holt's The Deceivers: Allied Military Deception in the Second World War illuminates, Allied arts in this field were far more expansive and sophisticated than prior histories revealed and worked across the spectrum, from tactical to strategic. The grandest of the deceptions, christened Fortitude, exquisitely coordinated code-breaking, double agents, simulated units, and decoys in order to convince the German high command that the landings in Normandy were a feint. The needs of operational or tactical deception prompted the creation of "Beach Jumper" units in time for the invasion of Sicily. Their array of boats, visual and sound effects, and phony radio messages created false impressions of landings. Operation Olympic, the planned initial invasion of the Japanese home islands, featured a vast deception plan to confuse the Japanese, from the tactical to the strategic levels, about the timing and location of the invasion. 10
Command and Control
Failure of the Anglo-Free French expedition to capture the French West Africa port of Dakar in September 1940 demonstrated to the British that it was imprudent to command an amphibious operation from a large warship, such as a cruiser or battleship, that might be summoned away on another mission. They began converting two merchant ships for the purpose of providing a joint headquarters afloat. The U.S. Navy immediately recognized the value of such ships and placed the first class of them on order even before having any operational experience. Besides permitting direct consultation between sea and land officers, the ships maintained plots of the air, surface, and land situation. These invaluable vessels also performed fighter direction. 11
Once the order to commence a landing was given, the lack of effective communications meant that wave after wave of landing craft would charge shoreward—sometimes to the wrong beach—heedless of any tactical or logistical considerations. This problem prompted the creation of a ladder of control vessels, prominently Patrol Craft (PCs) and Submarine Chasers (SCs). The PCs and SCs not only marked the line of departure, but they also regulated the flow of reinforcements and resupply. Perhaps the single most important contribution of this innovation came at Omaha Beach, where an unknown officer in a PC decided within an hour of the first landings to redirect subsequent waves away from the deadliest segment of the beach, fronting the Vierville draw—a decision that proved vital to victory. Actually locating individual beach segments and guiding waves in became the function of Landing Craft, Control (LCCs). These boats were larger than an LCVP, heavily armed, and fitted with radar and radios. 12
New Ships and Craft
The third level of development involved new species of landing ships and craft. This is largely a story of American designers transforming British concepts into hulls. The single most compelling challenge emerged immediately after Dunkirk: transporting a tactically significant number of tanks and depositing them in good order on a beach in northern Europe. The British swiftly devised Landing Craft, Tanks (LCTs) that generally carried three to five tanks. They also looked to something larger and invented the well-decked Landing Ship, Dock (LSD), effectively a powered dry dock capable of hauling tanks already loaded in landing craft. This proved to be a fruitful long-term concept, but too sophisticated for mass production. An American engineer, John Niedermair, conceived the amazingly versatile but simple, blocky, and plodding Landing Ship, Tank (LST) that proved the linchpin of landings from 1943 onward.
13 A British specification for a smaller vessel to carry a raiding party gave rise to the Landing Craft, Infantry, Large (LCI(L)). It evolved into a craft that could lift a rifle company and deliver it to the beach via gangways on each side of the bow (although late models featured ramps). American designers then created the Landing Ship, Medium (LSM), essentially an enlarged LCT able to keep pace with the LCI.
14 When the Marines examined the problem of attacking Tarawa Atoll in the Gilberts, they faced the challenge of breasting the fringing coral reef and for the first time intentionally confronting formidable beach defenses. The LVT could vault the reef, but the available vehicles, conceived strictly as amphibious motor transport, needed much more armament and armor to convert them into assault vehicles. Frantic efforts readied just enough of them to make the costly but successful assault on the main island of Betio. From that operation forward, the LVT was reborn as an assault vehicle. Moreover, LVT hulls were converted into amphibious light tanks to escort troop carriers and support Marines beyond the beach.
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