In the spring of 1944, the Japanese garrison on Saipan knew exactly what was coming and knew it could not stop it. The warnings were written down in at least six surviving staff papers, each one a different angle on the same catastrophe, and each one was clear enough that no one could claim later that they had not seen it coming. Twelve lookout stations stood along the shore of Saipan, built in the year before the Pacific War under a Japanese naval appropriation that officially listed them as lighthouses. Each came with barracks, a command post, an ammunition shed, and a man with binoculars watching a great deal of empty water.
That money bought far more than lookouts. From 1934 to the autumn of 1940, the Japanese government appropriated at least 14. 5 million yen for building in the Marianas alone. A further grant the following September covered barracks, baths, latrines, kitchens, infirmaries, storehouses, workshops, torpedo sheds, garages, and air-raid shelters.
The order authorizing it stated in writing that the buildings were for a base force and a defense force, both of them fighting units under Japanese naval organization. The naval unit already on the ground spent the latter half of that year on a task with nothing defensive in it: planning and preparing the invasion of Guam. For most of the war after that, there was very little on the horizon to watch. The naval base force on the island numbered fewer than a thousand men in the spring of 1943 and had not reached 1,500 by February of the following year.
Then, on June 8, 1944, with the island a week away from the arrival of the largest fleet yet assembled in the Pacific, that same headquarters issued an order moving 2,500 soldiers off Saipan to other islands in the group. That order was a command acting on its best reckoning of where the Americans were going. The naval high command had settled on the Palaus or the Carolines, somewhere to the southwest. After the carrier raid on the Palaus at the end of March, the loss of Hollandia in April, and the fighting around Biak in May, Saipan was thought to be a target for later in the year.
As late as June 14, with the bombardment already falling on the cane fields, Vice Admiral Chuichi Nagumo was still putting it in writing that the Americans would land in the Marianas this month or the next. Saipan, underneath all of this, was a sugar island with three plantations and two mills, each mill able to take 1,200 tons of cane a day. The molasses went into alcohol, and the alcohol went into a synthetic Scotch whiskey, a port wine, and four or five other bottled products made for sale back in Japan. What the Japanese officers stationed there had been putting on paper through the spring is a different story from the one their own headquarters believed.
Six of those papers survive. Run backwards from the invasion, they make a sequence. The last of them is dated May 31, two weeks and a day before the landing. It went out over the signature of the chief of staff of the 31st Army, a post held since the end of February by Major General Keiji Igeta, and it is a survey of the defenses of the various islands.
Igeta wrote that fortifications could not be strengthened to any worthwhile degree without materials fit for permanent building, and then he listed them, because listing them was the entire point: cement, steel reinforcement for the cement, barbed wire, lumber, none of which could be had in the islands. Without those materials, he wrote, the number of soldiers standing on the ground made no difference, because men with nothing to build with could only fold their arms, and he called the situation unbearable. He asked for the matter to be dealt with at once. A staff officer is permitted to say a great deal in a paper of that kind, and Igeta said very nearly all of it.
The one thing he did not say is what would have to be true for his request to be answerable. Before that came May 20 and a paper headed as the outline of the defensive plan of the Northern Marianas force. It sets out what the garrison would do. Units would build strength enough to destroy an American landing force at the water’s edge.
The islands would become a fortress, and the airfields would be held. Then the plan says of itself in its own text: “Although tardy,” and promises field positions finished in the first ten days of June, with permanent works to follow afterwards at the important points. Nothing inland is mentioned in it anywhere. Everything in the plan happens on the beach, which on a flat coral atoll is orthodox Japanese practice and which on a volcanic island fourteen miles long with a 1,500-foot mountain in the middle of it leaves the best ground on Saipan unfortified.
The officer who drafted it was working against a clock he did not control. The army’s own program called for field positions within a month of a unit’s arrival and permanent works within three months. The engineers responsible for the permanent works, the 7th and 16th independent engineer regiments, did not reach the island until April. The division meant to hold Saipan, the 43rd, did not arrive until the first week of June.
There is a concrete measure of what a beach scheme meant on the ground. On May 25, the commander of the 136th infantry regiment issued an operations order for the central sector, which covered most of the shoreline where the 2nd Marine Division would come in three weeks later. Four rifle companies and an infantry gun company went into the front line on the beaches. The reserve for that whole sector amounted to two-thirds of a single company.
One item in the plan did get built in quantity. It called for dummy emplacements laid between the real strong points and between the coastline and the support line, thickest of all along the stretches where a landing was least likely, so that American gunfire would go into empty ground. The Americans photographed a good number of them, and there is a picture in the official history of a dummy searchlight platform on the East Coast that is convincing. The paper before that is dated May 10, and it is the one that answers Igeta.
Headed as the state of supplies and materials in the Southern Marianas, it sets out the freight position in a single line. One ship in three was being sunk. Another was being damaged. Every item on Igeta’s list, every bag of cement and every coil of wire, had to arrive from Japan in a hold, and holds were the thing the Japanese no longer had.
The answer to the last warning was already in the files, written three weeks before the warning went out. So the question stops being whether the warnings were clear. They could not have been much clearer. The question is where they went and what sat on the other end.
The Japanese command arrangement in the Central Pacific in 1944 did not have one obvious upward address. On paper, the 31st Army answered to the Army section of Imperial General Headquarters in Tokyo. In March, a new naval command, the Central Pacific Area Fleet under Nagumo, went in above both the Army and Navy forces across the Mandated Islands and the Bonins. The Army objected to serving under an admiral.
That argument ended on March 15 in a compromise by which each island would be run by whichever officer on it was senior, and Nagumo and Lieutenant General Hideyoshi Obata agreed between themselves, out loud and without writing it down, that neither would take full authority over the other. It left the theater without a supreme commander. Igeta’s report of May 31 is addressed to the chief of staff of the Central Pacific Area Fleet, whose headquarters sat a short walk from his own on the same island. A Japanese naval commander taken prisoner on Saipan afterwards called that headquarters an administrative shell with no tactical meaning, an organization that never got past being an arrangement on paper.
The next paper has no date on it at all in the copy that survives. It is a 31st Army table showing the ammunition needed at once for anti-aircraft guns and machine cannon, the sort of table somebody types after doing the arithmetic and finding the answer frightening. The allowance for those weapons on Saipan was three units of fire. The regiment on the island and its two attached companies did not hold one.
And a unit of fire was 4,800 rounds. The same shortage ran through every area the 31st Army was responsible for. None of this stayed abstract. American troops moving inland in June would find heavy weapons on Saipan, from 200-mm mortars up to 5-inch coastal guns along with searchlights and anti-aircraft pieces, sitting in naval depots chained to railway flatcars, packed in grease, beside gun pits dug halfway and then abandoned.
The garrison had no horses and almost nothing that could travel across country. The only machines for shifting artillery were rear-drive trucks built for roads, so guns that men could not drag by hand stayed where they were. The pieces that did get into position had been sighted in with care on the obvious targets, on the breaks in the reef above all. But each battery had done that sighting alone, with no common survey control behind it.
Japanese artillery on Saipan was never able to mass its fire. The airfields tell the same story in a different currency. In March, both the Combined Fleet and the Central Pacific Area Fleet issued orders for a rapid build-up of air bases, the aim being a large number of rough fields at speed, brought to a finished state later. Each one tied into the ground defenses, and each air unit trained to fight on foot.
The program came to 14 airfields and two seaplane bases across the group. Normal facilities were to be complete by April. When the Americans arrived in June, nine of the 14 were operational. Back at the first week of March, the papers stopped being requests and became an alarm.
On March 3, the 31st Army issued an emergency plan for the defense of the archipelago, and at that date, the archipelago was all but undefended. The following day, the Army abolished civil government on Guam and brought in martial law across the islands a few days behind it. Americans later took excerpts from the Army Headquarters Staff Diary covering late winter into March, and the diary puts the position without decoration. The American strikes had alarmed the Central Command.
After the carrier attack on the Marianas on February 22 and 23 had shown how thin the defenses were, Tokyo expected an invasion within the month. The same diary shows the headquarters trying to turn the Eighth Expeditionary Unit North into the Marianas instead of letting it go on to Truk. The headquarters thought about that and then let the unit go on south. That brings the sequence round to the assumption buried in the premise.
Tokyo was not asleep, and Tokyo did not ignore its officers in the islands. Tokyo had already answered in February, at once and at the highest level. The staff of the 31st Army had been getting ready to move out to the Marianas when the Marshalls fell. And once the islands had been hit from the air, the Prime Minister, General Hideki Tojo, ordered them to leave for Saipan the very next day.
Between January and the first days of June, the Japanese put about 45,000 soldiers aboard ships bound for the Marianas. Tokyo had answered, and the answer was an army, and the army went by sea. At least 12,000 of those men were aboard hulls that were torpedoed on the way out. Many of the ones pulled from the water were carried on and landed anyway, on whatever island the surviving ships were nearest, which meant a large share of the reinforcement came ashore without weapons, without papers, belonging to units that were somewhere else entirely.
Survivors of one convoy bound for Yap were still sitting on Saipan in June waiting for shipping. So were men of a regiment that had been going to the Palaus. In May, the army renamed and reorganized its units across the whole area so that a garrison headquarters could not always say with confidence what it held. At that point, the six papers stopped being six unrelated problems.
Every officer who wrote one of them was describing the same American capability from a different angle, and not one of the six is able to name it as a single thing. The supply paper of May 10 sees a freight ratio. Igeta sees an absence of cement. The ammunition table sees rounds not held.
The Northern Marianas plan sees time that has run out. The staff diary sees aircraft over the islands in February. What all of them were looking at was an American campaign against the Marianas that had been running for four months before a single rifleman came ashore, fought at sea and in the air, against shipping by submarine crews and carrier pilots that almost nobody in the garrisons would ever set eyes on. Most of what is known about any of this survives because a Japanese clerk filed a paper, and later an American translator gave that paper a number.
The limits are worth stating. These papers are known today as American translations of captured Japanese originals, given translation numbers by Pacific Ocean Areas Intelligence or by the landing force in the field, and the surviving copies show the addressee far better than they show the routing afterwards. Igeta’s report went sideways to a naval headquarters on his own island rather than to Tokyo. The ammunition table carries no date at all, so its place in the sequence is a reasonable guess and nothing firmer.
Which of these specific warnings reached which desk in the army section in Tokyo, in what form and in what order, is not something the surviving paper establishes. The first of the six is the plainest, and it asks for nothing. It is an arrival report written in the first week of March about what had just come ashore. The 18th infantry regiment had sailed from Ujina in Japan on February 26 aboard three troop ships, part of the 29th division being shifted out of Manchuria to hold the islands.
Three thousand and eighty men were aboard the ship that was hit. One thousand, six hundred and eighty-eight of them came out of the sea alive. What the regiment still possessed when it stood on Saipan went up the chain as an inventory: seven rifles, one grenade thrower, two light machine guns, and 150 bayonets. The ship was the Sakito Maru, hit late in the afternoon of February 29, 1944, by an American submarine that did not come home afterwards and never reported the attack.
Three and a half months later, the Americans landed.