amphibious warfare

amphibious warfare is the invasion of enemy-held territory from the sea. In the west it is at least as old as the battle of Marathon ( 490 bc) while in the Far East Japan had practised it beyond its borders even before then. During the Second World War it meant transporting specially trained troops to a designated landing beach in enemy-held territory; putting them, their tanks, artillery, and stores ashore from landing craft under an umbrella of supporting fire from the air and sea; and ensuring that the build-up in men and matériel was sufficient to overwhelm any opposition and to secure a beachhead from which an advance inland could be made.

Undertaking such an operation implied the full integration of all air, land, and sea forces, from the planning stage onwards, a new concept. Churchill called it triphibious warfare and it was, according to both Admiral King and Eisenhower, the most difficult to mount as it required careful planning, special training, and a high degree of technical competence on the part of the participants.

Between 1939 and 1942 methods were crude and techniques often faulty but by 1945 the US Marine Corps in the Pacific war had brought amphibious warfare near to perfection. Terminology varied, but by 1945 a landing force was normally divided into assault formations, which invariably included a floating reserve; follow-up formations; and build-up formations. Assault formations were ‘combat’ stowed—that is, supplies and equipment were loaded so that they could be unloaded in the order they were needed ashore—but build-up formations were stowed to make the most economical use of space, while the follow-up formations were a mixture of the other two, which was known as ‘tactical’ stowing. Assault forces were landed from landing craft or amphibians formed into ‘flights’. A flight usually carried a complete military unit and each was broken down into ‘waves’. Each wave was timed to touch down together and they were arranged so that a military unit was landed in the correct tactical order. They were formed up out of gunfire range on a line-of-departure which ran parallel to the landing beaches and was normally marked by control boats. Equipped with special navigational aids, including radar, the control boats also guided the assault waves in and then shepherded the subsequent traffic to and from the beach, always a major problem in any amphibious operation.

Early amphibious operations did not have this degree of sophistication, but their most important, and most vulnerable, moment was always when the first wave of troops hit the beach, and all calculations, including the complicated timetable for air and sea support, were tied to it. Amphibious doctrine recognized that this moment, generally known as ‘H-Hour’, could be altered by circumstances beyond the control of the planners after the operation had been launched. If this happened all other activities relating to the landing had to be altered, too, which brought about the terminology, ‘H-Hour minus 32 minutes’ or ‘H-Hour plus 12 minutes’.

The first practitioners of modern amphibious methods were the Japanese, who landed troops from a specially constructed landing ship at Tientsin in 1937 at the start of the China incident. But unlike the Allies, whose navies predominated, it was the Japanese Army which developed the necessary expertise in amphibious warfare and developed and constructed the specialized landing craft, and all large amphibious operations were reserved for it. The Japanese Navy, though in theory responsible for the assault phase of any landing, in practice took on a supporting role, its capture of Wake Island and Guam being notable exceptions. The necessity for local air and naval supremacy, for careful planning, intelligence, and surprise, were well understood. Night landings were preferred to gain surprise, and to avoid air attacks, but also because the Japanese were adept at night infiltration of their opponents' defences. The principal drawback to landing at night, confusion, they overcame by sound doctrine, rigorous training, the formation of élite troops for arranging the disembarkation, and the liberal use of luminous paint. Japanese amphibious doctrine, though sound, tended to be over-rigid. This gave the participants little flexibility to cope with the unexpected, but the numerous amphibious operations Japan mounted in 1941–2 met with little opposition. It was only the Americans at the battle of Midway and during the Guadalcanal campaign—both amphibious operations nipped in the bud—that stopped Japan expanding further.

The Germans mounted the first amphibious operation of the war in Europe, and a brilliantly successful one, when they invaded Norway in April 1940 (see Norwegian campaign). Uniquely for them they formed a special temporary joint staff to do so. However, the Wehrmacht was really only geared for land warfare. It jibbed at invading England in 1940 (see SEALION), though it did undertake a number of amphibious operations in the Baltic Sea in June 1941, and later in the Black Sea. These were both areas where the Soviet Navy also launched large numbers of landings. Early German pressure during the German–Soviet war meant that many were undertaken as defensive measures to aid the Red Army on shore and they were often inadequately planned and hastily improvised—according to one Soviet source 61 of the 113 Soviet amphibious operations mounted during the war were prepared in less than 24 hours (see Bartlett below). Proper co-ordination between the services was often lacking. Also, the Soviet Navy had no specialized landing craft, so that the different speeds, general unseaworthiness, and low carrying capacity of the boats used often resulted in troops being landed at different times in insufficient quantity and in the wrong places. Under these circumstances it is laudable that, according to another Soviet statistic, surprise was achieved in 76 of the operations (ibid.).

The Soviets learned quickly from these early mistakes. They continued to lack specialized landing craft (though some were acquired under Lend-Lease very late in the war), but their later amphibious operations, such as those in Korea, were carefully planned and properly co-ordinated, and had the proper level of air and sea support. By 1945, 40 naval infantry brigades had been formed for amphibious operations, and it has been estimated that 340,000 men took part in them.

Though supporting the Red Army with amphibious operations was one of the Soviet Navy's principal functions, amphibious warfare remained peripheral to Soviet strategy as a whole. To the British and Americans, however, it was central to their conduct of the war. In June 1940, the British, who had practised amphibious warfare for centuries, formed a new headquarters, Combined Operations, their term for amphibious warfare, to take the war to the Germans. The first permanent, fully integrated, inter-service organization, its major contributions to the Allied war effort were the development of larger landing craft and proper methods of training, and the mounting of a series of raids where many practical lessons were learned. After the Dieppe raid of August 1942 it was recognized that a heavy preliminary air and sea bombardment was essential. Equally important were surprise, proper intelligence on such matters as beach gradients and heavily defended beaches, and the necessity for close support landing craft which could continue firing until the troops were almost ashore. Inadequate communications also highlighted the necessity for a specialized HQ ship to control the operation, a lack some American operations continued to suffer until January 1944.

The North African campaign landings of November 1942 were mounted too soon after Dieppe for some of these lessons to have been absorbed, while others were ignored. Lack of training and inadequate surveys of the beaches beforehand caused the loss of 94% of the first wave of landing craft at Algiers and 35% at Casablanca. But there were no specialized beach recovery and repair teams to salvage damaged craft and vehicles; no equipment to bridge the water-gap between landing craft and shore; and no properly trained beach parties for unloading and handling supplies. Men drowned because they were overburdened and the US ship-to-shore technique, where infantry, armour, and artillery all had to be laboriously transferred from large ships to small landing craft, proved unsatisfactory. It was just as well that the maintenance of total secrecy was the one unqualified success of the landings, as this resulted in their being largely unopposed.

By the start of the Sicilian campaign the following July many of these faults had been corrected. The beaches were properly surveyed by Combined Operations Pilotage Parties; larger landing craft enabled a shore-to-shore technique to be employed by some of the assault force; specially converted landing craft delivered a last-minute bombardment; and the new amphibian DUKW, pontoon causeways which bridged the water gap, and specially trained beach parties speeded the handling of sup plies, armour, and artillery ashore. However, the British did not develop really successful beach organizations—they called them ‘bricks’—until the Salerno landings in September 1943.

The ability of the Americans to match British experience at this time was undoubtedly due to the US Marine Corps who were early experimenters in amphibious techniques and doctrine. Between the wars they had begun to tailor their weapons and tactical units to fit the ships transporting them; experimented with the Higgins boat and with amphibians; introduced the technique of combat loading; helped evolve the Attack Destroyer Transport designed to carry a marine raiding force; and developed the use of close air support with the navy which had been first practised in Nicaragua in the 1920s.

Their exemplary record in the Pacific notwithstanding, the greatest contribution the marines made to Allied victory was doctrinal. Apart from the six marine divisions which fought in the Pacific war, they trained the 1st and 9th US Infantry Divisions which landed in North Africa, Sicily, and Normandy (see OVERLORD); the 3rd US Infantry Division which landed in North Africa, Sicily, and Anzio; and the 7th US Infantry Division which recaptured Attu and Kiska during the Aleutian Islands campaign, seized Kwajalein during the Marshall Islands campaign, and landed on Leyte (see Philippines campaigns) and on Okinawa.

Though the marines were brought to the brink of disaster at the start of their first amphibious operation, Guadalcanal, their doctrine soon proved itself viable, and in MacArthur'sSouth-West Pacific Area US forces soon became experts at this kind of operation. Their first real test was a series of operations (CARTWHEEL) designed to isolate and reduce Rabaul began in June 1943 with the New Georgia campaign landings. These were accomplished at a speed the Japanese regarded as miraculous and by the time the campaign had been completed, and the New Guinea and Philippines campaigns also won, MacArthur had become an expert at, to use his own terminology, ‘hitting 'em where they ain't’. He was often able to leapfrog heavily defended areas and then isolate them, and could also frequently maintain surprise before landing on comparatively lightly defended beaches. He was also sometimes able to employ the ‘amphibious end run’ where secondary landings were made to the rear of the main ones. This ‘hammer and anvil’ effect of crushing the defenders between two blows was used most successfully during the Leyte landings in October 1944. Between Leyte and the end of the Pacific war, MacArthur's Eighth Army made 52 amphibious landings; in one 44-day period there was a landing every day and a half.

The marines who took part in the spectacular drive across the central Pacific, which started in November 1943, fought under different conditions, for their objectives were often too small and too obvious a target to avoid the Japanese defences. Instead, techniques were devised for landing on fortified beaches where surprise or light opposition could be discounted. Known as amphibious assaults, they required the use of armoured amphibians, total isolation of the objective, and heavy, sustained bombardments. To implement them the US Pacific Fleet, supported by a logistics system astonishing in its scale and efficiency (see also Fleet Train), was divided into three parts: the amphibious force, a vast array of landing ships, transports, and close support craft for landing the marines; the bombardment fleet, which comprised the older battleships supplemented by cruisers and destroyers, and later by escort carriers; and the fleet carriers and their escorts which sealed the objective from any reinforcement and protected the landings from air attack. With surprise of no consequence, bombardments often lasted days, and sometimes weeks, and the landings took place in daylight to maximize the accuracy of the preliminary bombardment.

These techniques only evolved as the Pacific war progressed. Those used at Tarawa, the first central Pacific objective, failed to work as the bombardment saturated the island without destroying its fortified positions. Because of poor communications (a specialized HQ ship was not used) the bombardment was also lifted too early and there were too few amphibians (LVTs) to cross the coral reefs that, because the tide had been incorrectly assessed, barred the way for landing craft. The result was heavy marine losses with the Japanese very nearly inflicting a crushing defeat on the shoreline.

Improvements followed quickly for the seizure of the Marshall Islands beginning in January 1944. A specialized HQ ship controlled the operation; the preparatory bombardment used interdicting fire from much closer inshore, and was supplemented by artillery positioned on unoccupied islets; star shell was used to illuminate ground liable to night infiltration by the Japanese defenders; and a last-minute bombardment was delivered by specially converted landing craft of which the rocket-firing variety (see rocket weapons) were the most deadly. LVTs, which took the entire assault force ashore, were taken as close to the beaches as possible by LSTs, underwater demolition teams were used for the first time to clear natural and man-made obstacles (see frogmen), and the US fleet, aided by ground fire control parties, remained to support the advance inland.

These techniques were so successful that they became standard procedure in the Pacific landings which followed. Though these did not always proceed smoothly—the Japanese displayed great courage and ingenuity in countering American tactics on islands such as Saipan and Peleliu—the Marshalls was a watershed in amphibious warfare in the Pacific. Tinian was called ‘the perfect amphibious operation of the Pacific war’, but the Marshall Islands showed how it should be done and by April 1945, when Okinawa was invaded, the US Navy and Marines had stood on its head the pre-war theory that the best way to defeat an amphibious operation was while it was taking place. At Tarawa the Japanese almost managed to do this, but at Okinawa they did not even attempt to defend the beaches. ‘The power of the American warships and aircraft,’ commented the Japanese commander on Iwo Jima which fell in March 1945, ‘makes every landing operation possible to whatever beachhead they like.’

In Europe amphibious warfare was shown at its most complex and ingenious during the Normandy landings in June 1944, the largest operation of its kind in the history of warfare. It was mounted in daylight and relied to a large degree on deception for its ultimate success. Within a month a million men were ashore, an astonishing feat to which every previous Allied amphibious operation of the war had in some way contributed.

The last amphibious operation of the war (ZIPPER) took place after the Japanese had surrendered as it seemed the most practicable way for the British to regain control of Malaya; and on 9 September 1945 their forces landed unopposed near Port Swettenham and north of Port Dickson.

Bibliography

Bartlett, M. (ed.), Assault from the Sea: Essays on the History of Amphibious Warfare (Annapolis, MD, 1983).
Clifford, K. , Amphibious Warfare Development in Britain and America from 1920–1940 (NY, 1983; despite its title this covers the whole war).
Fergusson, B. , The Watery Maze (London, 1961).