The Pacific War Companion

An extract from Chapter 13 ‘The Island Experience: The battle for Okinawa April 1–June 21, 1945’ by Major Bruce Gudmundsson

At the start of 1945, Japan was in a difficult position. Her most powerful warships had been sunk. Her best pilots had been shot down. The fortified islands that formed her first line of defense against the United States had been lost. As a result, her home waters were dominated by American submarines, her communications with the rest of the Japanese Empire were all but cut off, her cities were subject to regular aerial bombardment and her civilian population was on the verge of starvation. To make matters worse, the Americans had returned to the Philippines and the British were on the offensive in Burma.

Difficult as it was, the situation of the Japanese Empire was far from hopeless. The Japanese Imperial Army was still intact. Indeed, that army was not only the undisputed master of Korea and Indo-China, but was still winning significant victories against the Chinese. The nations of the anti-Japanese alliance, moreover, were beginning to tire of the high price of victory. If that price could be raised, they might be willing to negotiate a tolerable end to hostilities. Put more bluntly, Japanese success depended upon the killing of large numbers of American servicemen, for the United States was both the initiator of the demand for unconditional surrender and its chief advocate.

There were few places where the Japanese could fight the sort of battle needed to implement their strategy of attrition. The Philippines provided the attacking Americans with too much room for maneuver. Formosa was too easy to bypass, as were most of the other islands that were still in Japanese hands. Indeed, the only places where the Japanese had the wherewithal to fight a long and bloody battle were the main islands of metropolitan Japan and the substantially smaller island of Okinawa – the biggest island of the Ryukyu chain. Of these, the one closest to the American-held islands in the Central Pacific – and thus the most likely choice for an American landing – was Okinawa.

The peculiar size, shape and location of Okinawa made it the ideal place for the kind of battle the Japanese needed to fight if their strategy of attrition was to succeed. At 485 square miles, Okinawa was big enough to attract a sizeable American force, yet small enough to prevent the Americans from making full use of their numerical superiority. Because it was a jumble of long, thin peninsulae, Okinawa would severely limit the ability of the Americans to engage in the kind of rapid operational maneuver that was serving them so well in the Philippines. At the same time, the proximity of Okinawa to the island of Kyushu – home to a large number of kamikaze squadrons – would make it possible for the suicide planes to play their part in the campaign of attrition.

The advantages of size, shape, and location were greatly enhanced by the character of the Okinawan terrain. The seemingly random interaction of hills and ridgelines, rivers and ravines, fields and villages, small jungles and substantial towns broke the island into a large number of small compartments. Each of these compartments was a one-of-a-kind combination of the various components that made up the Okinawan landscape. Thus, rather than providing the combatants with a small number of large battlefields, Okinawa presented them with hundreds of tiny battlefields, each of which demanded that the tactics of both the attacker and defender be custom-tailored to its peculiarities. At the very least, this terrain would provide the Japanese defenders with a sanctuary that could not be taken from them without a long and bloody struggle.

The most optimistic of the Japanese schemes for killing Americans on Okinawa depended heavily on the kamikaze. These called for the Japanese ground troops on the island to allow the largest possible number of Americans to land. Once the Americans were firmly ashore, kamikaze planes and suicide boats would attack Allied ships in the waters around Okinawa, destroying as many as possible and driving off the rest. With no fighters overhead, no fighter-bombers on call from nearby carriers, and no gunfire coming from ships off the coast, the Americans’ ground troops on Okinawa would be deprived of the weapons the Japanese feared most. They would also be stranded – deprived of supplies, reinforcements, and hope. Once the American landing force had been suitably weakened, 100,000 or more Japanese fighting men on the island would then emerge from their sanctuary and, in a rapid series of bold counterattacks, completely annihilate the invaders.

More realistic proposals also put considerable faith in the ability of the kamikaze to inflict damage on Allied ships. The officers who put these plans together, however, were under no illusion about the outcome of the battle. They knew that, no matter what the Japanese did, the Americans would eventually triumph on Okinawa. Their only hope was that the American victory would be a Pyrrhic one – that it would be so costly in American lives that the United States would become extremely reluctant to invade any of the larger home islands. In order to maximize the American losses, the advocates for these less optimistic plans intended to make their stand in the southern third of the island – the home of the vast majority of the residents of Okinawa and the place where the compartmentalization of terrain was most pronounced. Centered on the ancient royal capital of Shuri, this area would become the scene of hundreds of small-scale, close-quarter battles – battles in which the big shells fired by American warships and the bombs dropped by American planes would have relatively little impact.

To enhance their ability to fight in the compartmentalized terrain of Okinawa, the most favored of the Japanese units on that island – the regular army units that were expected to do the bulk of the fighting – were richly supplied with close-range heavy weapons. Antitank companies generally had an official allowance of four 47mm guns; on Okinawa, such units were given six, seven, or eight of these high-velocity weapons. Other weapons were also provided in quantities greater than those called for in standard tables of equipment. Infantry squads, for example, normally went to war with a single light machine gun. On Okinawa, they had two or three light machine guns, as well as one or two of the ubiquitous ""knee mortars."" (Often described as ""grenade launchers"" or ""grenade dischargers,"" these handy weapons could fire a standard hand-grenade out to 170 meters, as well as a specially designed projectile out to 670 meters.) Additional close-range firepower came from special heavy weapons units – machine-gun battalions, mortar battalions, and light antiaircraft battalions. These provided rifle-caliber heavy machine guns, medium (81mm and 90mm) mortars, 320mm spigot mortars, and large-caliber (13mm and 20mm) antiaircraft machine guns to reinforce the organic weapons of the Japanese infantry.

The many second-line units on Okinawa – units made up of ground crew from the island’s airbases, sailors who found themselves without a ship, and army units of various types that had recently been converted to infantry – were not so well armed. As many of the weapons intended for them had been sent out in ships that had been sunk by American submarines, these units had to make do with a lower-than-normal scale of standard infantry heavy weapons. In many cases, however, they made up for this with skilful improvisation. The units made up of stranded sailors, for example, made extensive use of machine guns and automatic cannon taken from unserviceable aircraft. The mission of many of these second-line units, moreover, was different from that of the first-line units. They were stationed in places other than the main battle area, on the outpost line north of that area and on various outlying peninsulae. The task of these units was to harass and delay the Americans, inflicting losses while buying additional time so that the first-line units could improve their positions. Once this mission had been accomplished, the survivors of the second-line units were to find their way back to the main battle area and join the first-line units fighting there.

Third-line units – labor units and the local home guard (""Boetai"") – were in the worst position of all when it came to weapons. Those who were issued firearms were given weapons of considerable antiquity and doubtful reliability – some were single-shot weapons that had been in storage for a half-century or more. Those members of the home guard who lacked firearms were issued with improvised spears – bamboo poles tipped with bayonets. Such weapons, however, would play very little role in the fight for Okinawa. Rather than being given sectors of their own to defend, the third-line units were used to provide replacements for men of regular army units who had been killed or wounded. While this policy would create problems of its own, it allowed the Japanese to make full use of their most powerful close-range weapons.

At the heart of the Japanese concept for the use of close-range weapons was the principle of mutual protection. Instead of being concerned with its own survival, the crew of a Japanese heavy weapon was instructed to focus on the task of protecting other weapons in the defensive array. In particular, it was to cover the places that the attacking Americans would have to occupy in order to attack those other weapons. If every one did as he was supposed to, this system worked very well. Americans attacking one Japanese position would find themselves hit in the flank or rear by fire from other Japanese heavy weapons. If, on the other hand, the crews of machine guns, mortars, antitank or infantry guns failed to keep faith with their comrades, the whole system of martial altruism would break down. Instead of receiving fire from unexpected directions, the Americans would be free to focus their efforts on the Japanese weapons in front of them.

Close-in protection for the heavy weapons that formed the backbone of the Japanese defense came from snipers and men armed with knee mortars. Some of these snipers and mortarmen were co-located with the heavy weapons. Their purpose was to allow the heavy weapons to delay their fire until suitable targets presented themselves. Other snipers and mortarmen were posted outside the firing positions of heavy weapons, protecting them from American scouts that threatened to discover them before they opened fire. These fighters were protected by fighting holes that they called ""octopus pots."" (The name came from the resemblance of these simple one-man shelters to the cookware used for boiling cuttlefish.)

Substantial reinforcement for the Japanese heavy weapon positions was provided by lighter artillery pieces – 75mm field guns, 105mm field howitzers, and a variety of shipboard, coastal defense and antiaircraft cannon of various sizes. Instead of being kept to the rear of the main battle area as intact batteries, these pieces were distributed in much the same manner as infantry heavy weapons. That is to say, they were hidden in individual firing positions that were sited for mutual support. Thus, just as the fire of one heavy weapon served to protect the firing position of others, the fire of one artillery piece protected the firing positions of other weapons. The great advantage of this system was that it reinforced the network of positions for heavy weapons, ensuring that there were few places within the main battle area that were not covered with effective fire. The great disadvantage was that it was impossible to either mass the fire of several batteries, or shift the fire to hit targets of opportunity. Each artillery piece was aimed at a particular piece of terrain and could not, without enormous effort on the part of its crew, shift its fire to another.

The firing positions of both infantry heavy weapons and light artillery were hard to change because they were, quite literally, set in stone. More precisely, they were located in artificial caves that had been dug into the sides of Okinawa’s many hills and ridgelines. Many of these caves were quite elaborate, with multiple entrances, firing positions for a variety of weapons, simple living quarters, observation posts, and storage areas for food and ammunition, as well as provision for drainage and ventilation. The coral rock that most of these terrain features were made of was well suited to the building of these underground fortresses. With the consistency of concrete, it was soft enough to be worked, and yet solid enough to withstand heavy bombardment.

The larger Japanese artillery pieces – the 150mm howitzers, the 105mm guns, and the larger naval and coastal defense weapons – were organized in a more conventional manner. Though also kept in caves, they were brought out into open firing positions whenever they were needed to mass their fire in order to repel a major American attack or support an attack of their own. Because of the threat posed by American ground-attack aircraft, each such use of the Japanese heavy artillery had to be protected by the deployment of a considerable number of antiaircraft guns. Even then, fear of American counter-battery fire – particularly the heavy shells of the American battleships and cruisers – would ensure that each unveiling of the Japanese heavy artillery was a short-lived affair.

The Japanese defenses on Okinawa might well be described as a three-dimensional, multi-layered network of mutually supporting fire-sacks. Americans attempting to engage individual Japanese soldiers – the men armed with rifles or knee mortars – would find themselves surrounded by the fire of several machine guns, mortars, or infantry guns. Infantry units that managed to get close enough to endanger these infantry heavy weapons found themselves exposed to the fire of field pieces and antiaircraft guns. Similarly, tank units that went after the heavy weapons could do so only by exposing themselves to the fire of antitank guns.

Japanese preparations for the defense of Okinawa were greatly hampered by the lack of common vision. A substantial portion of the Japanese leadership – including the senior staff officer on the island, Lieutenant-General Ishama Cho – believed that the key to success on Okinawa lay in vigorous counterattacks conducted on the largest possible scale. For them, the caves were shelters and storage facilities rather than fighting positions. Indeed, a number of unit commanders issued directives forbidding their soldiers to fight from their caves. A second faction believed that the best way to kill large numbers of Americans was to wait patiently for the Americans to attack, to let them walk into the traps that had been set for them, and then destroy them, one squad or platoon at a time, by fire and small-scale counterattacks. The most prominent advocate for this point of view was Colonel Hiromichi Yahara, operations officer of the Thiry-second Army and thus the second-ranking Japanese staff officer on Okinawa.

Because of the lack of a common vision, the Japanese defenses on Okinawa were neither optimized for large-scale counterattacks nor fully prepared for a protracted series of smaller defensive battles. The way that the field artillery was distributed, for example, greatly reduced its ability to mass its fire and thus conduct the kinds of fires best suited to a large-scale counterattack. At the same time, the subordinate commanders who designed the defensive positions for their units often failed to provide for such things as mutual support and surprise. As a result, there were many cases where infantry heavy weapons and light artillery pieces were sited to provide long-range fire over open ground, rather than surprise fire at close range. As such firing positions were predictable, they were vulnerable to the long-range fire of American naval guns, artillery, and tanks, as well as assault by American ground attack aircraft. Likewise, there were many cases where neighboring units failed to harmonize their fire plans, thereby leaving gaps that the Americans could exploit.The one thing that all Japanese decision-makers on Okinawa agreed upon was that it was pointless to try to defend the place where the Americans were most likely to come ashore. This was a piece of relatively flat land just south of the narrow waist of the island that separated the jungle-covered mountains of northern Okinawa from the densely inhabited south. The west coast of this plain was formed by eight more or less continuous miles of the best landing beaches on Okinawa – the only place where four American divisions could land abreast of one another. Called ""Hagushi"" by the Americans (for a village located near its center), this landing beach had the additional advantage of being close to two of the four major airfields on the island.

In order to avoid fighting on the beaches, the Japanese all but evacuated the waist of the island. The only unit that remained there was a provisional regiment of laborers and service troops. The Japanese deployed the bulk of their forces – all but two of their infantry battalions, all of their 90 or so tanks, and most of their artillery and heavy weapons – in the southern third of the island. The remainder of the Japanese troops – two infantry battalions and a company of 81mm mortars – were stationed north of the airfields. These were the only Japanese units in the northern two-thirds of the island.