Politically the boundary is near Hollandia at 141 degrees east longitude, and the whole island is divided into two halves. The northern half of the east section is under Australian mandate, while the western half, Dutch, is now West Irian.

The Mountain Chain

There is a large backbone of mountain range which runs lengthwise from the head of New Guinea to the tail, and this forms the topographical framework. This mountain chain has peaks about the height of Mount Fuji, the highest being called Wilhemina and about 5000 metres high; it is always snow covered and can be seen from all over New Guinea. The four large New Guinea rivers which flow down from near this high mountain range divide New Guinea into four equal parts.

Near the tail part of this central mountain range is divided into two by the Hagen tableland; the Owen Stanley Range, one of these two runs lengthwise throughout the tail as far as Rabi; it was the range which cut off the south East Detachment’s capture of Moresby. The Finisterre Range, runs from the top of the Hagen tableland eastward towards New Britain, crossing the Ramu River valley (it is the range which contains Sarawaged pass, surmounted with difficulty by the 51st Division during their advance from Lae).

Running lengthwise on the left bank of the Ramu River which follows the coast to the north west of the Finisterre Range is the Adelbert Range; its height is about 1000 metres, and it was closely related to the campaign which centred round Madang in 1943. The next most famous is the Alexander Range, which passes almost through the centre of New Guinea and runs roughly parallel with the north coast from the vicinity of Marienburg, on the left bank of the Sepik River. This range is the same height as the Adelbert Range, so was not a very big matter, but it was the most troublesome for the army; from the beginning of 1944 until the end of the war almost the whole of the army fought while crossing its northern foot or its southern foot – and whoever fought in New Guinea knows this mountain range best.

From a geological point of view, New Guinea’s period of formation is very recent; and its topography is wild. Roads are the exception rather than the rule; they are on the razorbacks, and if you are walking along the razorbacks it is just as if you were on level ground; but when you look down the sides at the valleys thousands of feet below, the slope looks extremely steep, more like a precipice, in fact. There are squalls that bring torrential rain; the rain comes down with terrific force, and what are usually waterless rivers become unobstructed mountain streams, suddenly changing into cataracts, plunging down to the sea in steps and stairs. It is hard to find words to describe how formidable this was.

The Finisterre and the other ranges are of course close to the coast; they are about 2ｽ miles wide, sometimes narrowing to 400 or 500 metres. The squalls resemble our summer showers in Japan but there is no comparison between the amount of rain that falls; the squalls are so heavy and violent that it is impossible to see objects 30 feet away. Not only that, but what was far worse, they often continued all day and all night. Usually, squalls in tropical regions temporarily leave the landscape further than the eye can see, but because of its situation and the mountain ranges, in New Guinea the moisture laden winds strike the high mountains and rain falls, and it is therefore quite customary for rain to fall continuously for long periods. Accordingly, as a result of the squalls and the excessive moisture there were many sicknesses and deaths. And I will later add a supplementary explanation in connection with the rivers.

In a topographical respect, the jungles of New Guinea were quite different from those of Malaya and other places. The New Guinea jungle, as a result of the squalls and the precipitous nature of the slopes, has, inside it, clearings just like the woods in a park. Forests where axes have not been known for an eternity – but is eternity yesterday? There were many occasions when we thought it might be the day before yesterday. Since there were these comparatively long distances in the woods, movement of units was comparatively easy, and again, although fighting in the woods was difficult, it was possible. Of course, in the lowlands, particularly in the humid regions, the jungle contains rattan and other creepers in profusion, so that there are places which are impenetrable.

The River System

As I have mentioned before, the starting point for New Guinea’s river system is the high part of the Wilhemina Mountain region, and it is clearly divided into four main river systems. There are, in fact: in the north west, the Memberamo River system, which flows into Helvink Bay; in the south west, the Digul River system which flows into the Arafura Sea; in the north east the Sepik River system and in the south east the Fly River system which flows into the Papua Sea. Everywhere there is abundant volume of water, and great depth, so that it is possible for steamboats to navigate far upstream. For the future development of New Guinea, these rivers must be made great transport arteries, whereas at present they are used by only a few native canoes.

As I have mentioned before, the origin of New Guinea’s water system is connected with the squalls; when the north west wind strikes the mountain ranges near the coast, most of it becomes rain, while the remainder falls mainly on the central ranges. Therefore the volume of water in the rivers is plentiful in the northern section of the mountains and less in the south. Since the coastal range is extremely close to the coast, although there is a great amount of rain, there is no immediate emergence of great rivers; although they are wide, the depth of water is very slight and they can be forded easily at any place. But when the squalls came they changed to raging torrents because of the steep nature of the terrain; so that the maintenance of bridges is very difficult, and neither men nor horses can cross them. The rivers which rise in the central range have a very plentiful flow of water because of the large area of the watershed and the comparatively gentle terrain. The side away from the north west wind has little rain, and has formed grassy plains. The region south of the Finisterre Range was Nadzab plain, which became an American Airfield and on the south side of the Alexander Range there was the Sepik plain. The natives call this grass plain kunai. Since the kunai are of gentle terrain, and do not have raging torrents, they are extremely suitable for cultivation.

Besides the four large rivers I have mentioned, there were others which concerned the forces – the Markham and the Ramu. These both rose in the Hagen Range, in the Central Ranges. The former flowed through the south side of the Finisterre Range and into Huon Bay, forming the Nadzab plain. It was here that in September 1943 the Australian and American Group dropped paratroops to attack the rear of our positions. The Ramu River is very close to the main stream of the Sepik and as they flow more or less connectedly with each other they have formed a watery belt. At the beginning of 1944 six parts of the army crossed these two big rivers, the Ramu and the Sepik, on the way to Wewak; when, sick and weary, they encountered this watery region, at the end of their strength many of them had to be buried in this clay.

The rivers of New Guinea are natural rivers in the true sense of the word, and untouched by man since the formation of the earth's crust, they have looked the same since antiquity. There are no bridges or dikes, and as the water flows whither it will, yesterday’s deep pools become today’s shallows; it is just as though it were laughing at mankind’s busy and bustling activities and its ups and downs, successes and failures. When you look down from an aeroplane, those on the plain seem to be winding and zig zag, as though unrelated to our idea of time; there are others which flow down directly to the sea from the mountains, as though drawn in a straight line. But these straight rivers do not have a very great natural force; at their entrance to the ocean they make either a left turn or a right turn and have a narrow mouth as a rule. For this reason the rivers of New Guinea, apart from the four big ones, are not suitable for navigation. The coastline is very monotonous and there is a scarcity of good harbours, so that from shipping point of view the prospects of future development are very poor.

Coasts and Harbours

As I have already mentioned, the coastline is monotonous, and the coral reefs which are a feature of the southern sea area make it hard to find a good harbour. It is also important whether or not a harbour affords shelter from the north west wind, and along the most of the coast which faces the north west, there is a lack of good harbours.

It is no exaggeration to say that there are coral reefs everywhere on the coast of New Guinea. Perhaps it is more appropriate to say that New Guinea is an island formed from coral reefs. Even in the hinterland of the island, even on the tops of the ranges, there are coral outcrops everywhere. Probably the coral reefs which originated on the seabed cropped out at the same time as the land rose. The growth of coral usually takes place near the shore, where there is mixing of fresh water and salt water, and it’s found in particular near river mouths. It is of course a serious obstacle to coastal sailing with ships that are fairly big.

Even if there were no coral reefs in this sea it would be no good for ships.

I should mention the harbours in the eastern part of New Guinea – Lae, Wewak and Hollandia. These three harbours were the crux of the army’s New Guinea campaign. Lae is on the inside of the Huon gulf, which is sheltered from the north west wind by the Finisterre Range overlooking the mouth of the Markham River. Southward there is a huge U shaped bay enclosed by the Salamaua Peninsula, and to the west there is the Nadzab grassy plain, permitting the construction of an airfield, so that it is a strategic point of sea, land and air communications. The 51st Division of our army fought desperately for 8 months to hold this fine harbour till the bitter end. Wewak, near the Sepik river mouth, faces the anchorages of Kairiru and Mushu Islands, but has the disadvantage of being exposed to the Ocean, and is therefore lost as a good harbour. The army made a base here and brought munitions from Palau. Since there is a comparatively large clearance between the coast and the Alexander Range, it was possible to build and airfield there; so the Wewak, Busu Airfield was built there, becoming the New Guinea air base. Everyone in the forces was well acquainted with Wewak.

The third best harbour is Hollandia. Hollandia is divided into two by Humboldt Bay and Tanamerah Bay. Both are good harbours, while on the land a level tableland surrounds Lake Sentani. It is a land and air strategic spot, and here the army had its rear installations second to Wewak, and this would have been established as a supply base if Wewak were ever abandoned.

According to Maj-Gen Eichelberger, this was the target for occupation when the American forces landed.

Besides these, other harbours in eastern New Guinea which were observed were Finschhafen, Madang, Alexishafen, Hansa and Aitape. Finschhafen is situated on the eastern tip of the Huon Peninsula and is the barrier to the Dampier Straits. Fighting for this point was the FINSCHHAFEN campaign of the 20th Division (Cho Group).

As harbours Madang and Alexishafen were of little value, but as they were situated between the Wewak base and Lae and Finschhafen, they were handy for liaison with Rabaul; therefore Army headquarters were established and for the first half of the New Guinea campaign this was the command centre.

Bansa was a forward supply base and on the harbour various transport battles were carried out. Since it was between the base airfield at Wewak and the forward airfields of Madang and Alexishafen, a liaison airfield was established there.

Aitape was a miniature Wewak and because of its situation was used as a liaison base for air and sea. It was captured in April 1944 as a result of the American landing. The forces covered by the rear of Wewak were entirely cut off from their supplies and there followed the Aitape campaign by the entire army who died bravely for the tranquillity of their homeland, having planned never to retreat from Aitape.

From the above, it can be seen that from the aspect of communications and sea transport the harbours of New Guinea were of a low standard, and it was only because of the lack of good harbours that they were of strategic importance. A peculiarity of the New Guinea campaign was that it was a campaign of transport, so that the value of the harbours increased, and it was of prime importance whether or not one possessed them. Therefore it is no exaggeration to say that the fight for the harbours was the final point of the New Guinea campaign.

Weather

The north coast of eastern New Guinea, being in a southern latitude of 4-5 degrees, is a land of perpetual summer in the literal sense. So everybody probably imagines that it is scorching hot weather that makes it impossible to sleep at night; but this is not the case with New Guinea. In the daytime on the low lands, exposed to the direct rays of the sun, it makes one think of a cauldron in hell, but on reaching the highlands, particularly in the mildness of the night, it is not as bad as Formosa or the Philippines. Really, in the daytime it is quite pleasant to seek coolness in the shade of the trees. On moonlight nights, living in a village in the highlands, it is just like mid-autumn in Japan. There are no four seasons of spring, summer, autumn and winter, so that as Japanese we lost track of the passing of the days. What gave them an unsatisfied feeling was that with the simple harmonic motion of the son no change was to be seen in the colour of the trees, so that one had no impression whatever of the four seasons.

In New Guinea there is a distinction between the wet season and the dry season. As I have stated, the violence of the rain is unbelievable; roads, for instance, would be wiped out and would become rivers. I think that is one reason why there are no roads in New Guinea.

I would like to mention an illustration in passing. Once an area Army Staff officer came to inspect the situation in New Guinea. I asked his advice: "New Guinea roads are very bad. How would it be if a ditch were dug?" I listened quietly and he spoke at length: "I don’t know if you know the New Guinea squalls, but if you dug a ditch, the squalls would bury it, and even if you remade it once or twice, there would be nothing that would be successful in this season of continuous rain. Since the Chief of Staff is an engineer, he considered this point from all aspects, but even the Chief of Staff rejected this idea." When he had made this explanation, the young Staff Officer blushed. I put out the lifeboat; he explained further about the New Guinea squalls, "You have not any experience in this sort of thing. I also had misconceptions about it. Five times the Army Engineers have built bridges, and on the sixth occasion they have given up. Since it was not yet the era of motor transport, somehow we had to make it possible to use motors so that food could be transported in sufficient quantities, so the first time it was washed away orders were given to rebuilt it. The second and third times the same. It took a week to build and then was washed away, and the difficult part every time was the metal coupling. There was difficulty in replacing this. It would have been different if a replacement could have been obtained from Japan, but nail and bolt type replacements were very rarely obtainable from Japan. If there were no metal couple it was impossible to build a bridge.

The next difficulty was to obtain piles. In the beginning it was possible to cut down trees near the bridge but gradually it became necessary to go a long way. Then when the bridge was completed, after a mere four or five days it was washed away again. Perhaps it was some use from a training point of view, but since the object was to allow motor vehicles to go across, not being able to use the bridge constructed with grain pains was a wasted effort." Thus I learned a lesson from this tale of experience, namely that pile bridges were no use in New Guinea, and that suspension bridges were the only sound plan. During the invasion of Germany this type was used almost exclusively.

Another peculiarity of New Guinea in regard to the weather was the dampness. Fighting was greatly affected by this dampness; in the first place there was trouble in keeping the moisture out of the powder and firearms. Fuses, etc. absorbed moisture and therefore would not fire. In a hard pressed attack from the enemy, one gambled one’s whole life on this one discharge, and after penetrating deeply into enemy territory and fighting against all sorts of difficulties, at the last moment, after all these efforts it could be defective. The despair and despondency this caused cannot be understood by anyone lacking experience of the battlefield. The second difficulty because of this dampness was concerned with dry batteries. Dry batteries are the life blood of wireless communications and the army’s wireless for operational purposes was beyond value for the units who were scattered so widely over this extensive island. So it was necessary for the communication unit to fight an unceasing battle against this natural enemy.

What did relieve the tedium for our men in New Guinea was the clearness of the atmosphere. It was purity itself – no sand and dust wreathing up to the sky, no soot and smoke staining the air with filth. The countless stars of the southern hemisphere, with the Southern Cross as the Imperial Throne, were much brighter than those of the northern hemisphere.

Communications

The only communication mechanisms in New Guinea were canoes on the rivers and airplanes on the land. There were horses, but before the war there were no motor cars at all. As I have previously mentioned, it was an extremely difficult matter to establish roads, because of the peculiar nature of the weather. Whether it was because they realised this, or whether it was a result of consideration of their area of practical use, the Australians abandoned roads in New Guinea and decided on the aeroplane as the means of land communication. So they built several hundred various-sized airfields; this brings misgivings as to why they should build so many in this as yet unopened, dark, large island. It was because Australia was managing gold producing operations in various places on the continent and it was necessary to be in touch with these places. Not only would it have been costly to build roads to take material there, but to maintain them would also have been very difficult, so that small airplanes were the most economical solution, and the safest. It was clear that in a sparsely populated area, with few vehicles, such as New Guinea, there was no necessity to build roads.

The natives used canoes and water transport. There were two categories of canoe – ocean going and river canoes. The canoe is an utsubobune (T.N. Japanese for canoe) propelled by oars. According to its size, it can accommodate twenty people or so, but four or five is the usual number. Ocean going canoes have an outrigger to help them ride the waves. Both types are primitive boats, quite unsuitable for carrying material. So it is no exaggeration to say that if these were the only form of transport in New Guinea, there was no transport in New Guinea.

I have now given a summary of the topography as it concerned the troops, and I think you can judge how it affected operations. I shall later explain something about the natives.

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