A soldier looks out across the deep valleys towards Ioribaiwa on the Kokoda Track  from a point where the road ends and the descent by foot starts. Photo taken in September 1942.

Of all the campaigns of the Second World War that can reasonably claim to have been fought on a logistic shoestring, New Guinea ranks high. The country's relative isolation, inhospitable terrain, enervating and malarious climate, and underdeveloped infrastructure meant that the maintenance and re-supply of military forces presented a continuing challenge. After a series of false starts, the Allies generally overcame their logistic difficulties; the Japanese did not. Therein lay the most important single factor in the campaign.

Military historian and former Chief of the General Staff, Lieutenant General John Coates, in the Oxford Companion to Australian Military History

During the Second World War, Australian troops fought in the deserts of North Africa, the fields and cities of Europe, and across the Mediterranean. But the geography of Papua and New Guinea was vastly different to those arenas.

The army fought battles on the ground. From the jungles of the Kokoda Track to the tidal swamps of Buna, Gona and Milne Bay. From the tall kunai grass and dense forests to the treacherous mountain ranges of the interior.

Aircrew operated in some of the most difficult flying conditions in the world to bring in troops and supplies. Meanwhile, the Navy played a role in protecting vital shipping lines. They also transported troops and supplies and repatriated the sick and wounded on hospital ships.

Before the war came, Papua and New Guinea had very little infrastructure. There were just a few roads and a smattering of basic airfields. All supplies needed to come by air or sea. Both the Allies and the Japanese built new airfields, and infrastructure at ports.

Both the Allies and the Japanese developed major bases in the region, from which they could send troops and supplies.

The Allies' main base was at Port Moresby. It started with just two airfields and a basic port. The Allies developd the base while withstanding regular Japanese airstrikes.

The Allies also established a major support base at Milne Bay, on the south-east corner of Papua. The Milne Bay base was home to 10,000 men and boasted three air strips and wharves.

The Japanese captured Rabaul, on the island of New Britain, in early 1942, and established their main base. They also set up bases on the on the north coast of the main island of New Guinea at Finschhafen, Lae, Madang and Wewak.

The Japanese forces faced the same geographical and logistical issues as the Allies.

After preventing the invasion of Port Moresby at the Battle of the Coral Sea, and defeating the Japanese on the Kokoda Track and at Buna and Gona, the Allies' campaign focused on severing Japanese lines of supply and communication to neutralise Rabaul.

Much of the interior of Papua and New Guinea was inaccessible to vehicles. Rainforests, mountains and river crossings dominated the landscape.

Troops often had no ground support from tanks. They had to walk for many kilometres in oppressive heat and humidity. Sometimes they carried up to 60 kgs each, plus ammunition.

During the Kokoda Campaign, the 7th division cut back rations to save weight. This led to vitamin deficiencies.

Ground troops relied heavily on airlifts and Papua New Guinean carriers.

During much of the war in Papua and New Guinea, the Australian and US forces were supplied by air.

It was a challenge to keep the ground forces adequately supplied, especially those far from a major Allied base. The Japanese often burned produce gardens as they retreated, so food was scarce. At times, however, Allied troops would barter between themselves for things like tobacco for fresh fruit.

Troop transport aircraft were vulnerable and often needed fighter escorts.

As troops were landing at Wau to defend the Wau airport, they came under fire from Japanese forces on the ground.

As they came in, they were only about 15-20 feet above the Japs front line so they were firing up through the aircraft... a lot of guys were wounded ... in the aircraft ...

Corporal Noel Anthony Carey, 2/3rd Independent Company (later 2/3rd Australian Commando Squadron). Read more about his experience.

Supplies were often dropped from aircraft without parachutes. Many items were lost or broken. Sometimes, supplies were wrapped in blankets for protection.

To solve this problem, the 'storepedo' was developed in Australia and used by the Allies in the Pacific. It was a cylindrical container with a hessian parachute. The container was designed to absorb impact with the ground.

Without access to fresh food, the troops ate tinned and long-life food. This included bully beef, camp pie, sheep tongues, haricot beans and tinned fruit, along with dehydrated egg powder and instant potatoes.

The rations did little to improve the troops' health and wellbeing, as Arthur Douglas Tucker, 75 Squadron RAAF, recalls:

They were feeding us on tinned bacon which was dreadful, tropical spread which was worse, baked beans, and somewhere or other they had captured (laughing) one of those Liberty ships full of goldfish, er, what do you call them? - herrings in tomato sauce. And that was what we were supposed to eat. And the baked beans would blow up in your stomach, you already had gastro-enteritis, and so ... there was nowhere to wash your clothes, so you'd take a spare pair of shorts down to the strip and when you landed you'd clean your aeroplane up, wash your shorts, put your other wet ones on, and so we lived in wet clothes.

Supply runs were also heavily dependent on the weather.

Private Ernest Bennett-Bremner, 2/2nd Battalion, remembers what it was like on the Beachheads:

All who fought on the beachhead knew how greatly their efficiency and welfare depended on aircraft being able to land ... or at least to drop their cargoes behind the lines. Anxiously they looked each morning towards the mountains, and they were much heartened when the clear sky heralded the approach of the transports and the top cover of fighters.

Aircraft not only dropped military supplies and rations. The troops also received morale-boosting mail and the occasional comfort food, like cakes and sweets.

Both the Allied and Japanese forces conscripted thousands of Papuans and New Guineans to help the war effort. They lugged heavy stores, ammunition and rations on their backs. They also carried wounded and sick soldiers back to medical help.

The Australians first used local carriers on the Kokoda Track. According to the Second World War Official History, Series 1, Volume 5, a carrier could carry about 13 days' worth of food. The track took eight days to walk, so carriers could only deliver five days' worth of food.

Captain Bert Kienzle of the Australian New Guinea Administrative Unit (ANGAU) took charge of hundreds of local carriers. Rather than carriers walking the entire track from start to finish, he organised a relay with staging points from which carriers worked sections of the Kokoda Track. This meant the carriers needed to carry fewer supplies for themselves and could carry more supplies and equipment for the Australian troops.

The publication Voices from War tells Papua New Guinean stories of the Kokoda Track.

The carrying of wounded up and down this mountain track was very difficult and very dangerous but the carriers tenderly took loving care of the patients. When it rained, Papuan carriers used leaves to keep their patients from getting wet. This was not an easy way but they did it lovingly and willingly.

-Sarah Sau Hiari, Papaki village

Merchant shipping played a major role in supplying troops and cargo. From January 1942, the Royal Australian Navy (RAN) protected shipping convoys. They prioritised military cargoes.

Despite the Navy's protective effort, in the period to August 1942, enemy submarines sank seven merchant ships and damaged another six.

A major shipping loss was that of the MV Macdhui in Port Moresby harbour in June 1943. The Australian Government used the merchant vessel to transport troops and supplies from Australia to Papua and New Guinea.

Later in the war, fighting concentrated along the north coast of New Guinea. The Allied northern supply line, particularly from Milne Bay to Oro Bay, needed protection. Smaller warships, such as the RAN's corvettes, escorted merchant ships.

The Japanese also relied on ships to transport troops and supplies. In March 1943, they made a risky attempt to move more than 6,000 troops across the Bismarck Sea. The troops were bound for the Japanese garrison at Lae.

The Battle of the Bismarck Sea saw the United States and Australian aircraft sink all eight of the Japanese transport vessels and four of the eight destroyers that made up the convoy.

It was a disaster for the Japanese. Of the 6,900 troops headed to Lae, only about 1,200 made it. About 2,890 Japanese soldiers and sailors were killed. Others were rescued and returned to Rabaul.

The Japanese didn't try to reinforce Lae by sea again.

The rainforests, treacherous mountains, ridges and gorges of the Kokoda Track have gone down in history. But there are similar stories across all of Papua and New Guinea.

Men had to walk for hours, sometimes days, in heat and humidity before fighting. The long kunai grass trapped the heat. The multiple river crossings without permanent bridges, or no bridges at all, slowed progress.

Australian troops spent six months on foot, fighting their way across the 'Bloody Ridges' between Wae and Salamaua.

As Signalman Lloyd Collins of 3rd Division Signals remembers:

… there was little conversation. You neither had the time nor the inclination. Talking required energy and energy was a scarce resource. When passing a mate you sometimes glanced at his face, a face dull from fatigue and dripping with perspiration. You saw his sticking clothes, his muddy boots and trousers. You noticed the heavy pack and you could hear his heaving breath as he struggled past. Then, as you pitied him and felt sorry for his plight, you realised that you looked the same to others. Even though no words were spoken the silent glance conveyed sympathy and understanding.

Later in the war, Australian troops fought along the 1,700 m high Shaggy Ridge, a 6.5 km ' razor-backed' spur. It was often blanketed in thick fog, greatly reducing visibility. Shaggy Ridge has just one single track along the ridge line. In places, it was 'only wide enough for one man to cross, with sheer drops on either side'.

It wasn't much better for the troops fighting in the coastal areas. Buna-Gona was home to tidal swamps, mangrove forests and impenetrable jungle. At Milne Bay, men slept in rain-soaked tents on muddy ground.

Air operations in New Guinea were also restricted by the weather and terrain. It took Allied aircraft days in poor weather to find the Japanese ships trying to cross the Bismarck Sea.

Weather also affected the Allied airborne landing at Nadzab. Lieutenant Jack Scott describes an aborted flight on 9 September 1943:

There was no seating accommodation; we sat on the metal floor and jammed ourselves against each other to protect the skin of our backsides as we were buffeted and slid around the floor of the aircraft. A few got sick enough to start an epidemic. The only repositories for our vomit were our steel helmets. Once filled we tried to hold them in an upright position until we landed.

The terrain created more problems for aircrew. Flying Officer Alex Miller-Randle, 4 Squadron RAAF, piloted Boomerang aircraft on tactical reconnaissance sorties.

Flying up a valley close to treetops was extremely dangerous because it was very difficult to judge the incline, [which was] often greater than the aircraft's maximum rate of climb, so that even with full throttle the plane could not climb out of the valley. Furthermore if the valley sides were … narrowing sharply, it was very easy to misjudge the point where there was enough turning space left. … There were many times when I thought I had misjudged it and came out with heart pounding.

The 3rd Field Ambulance left Adelaide on 25 December 1941. It moved into Murray Barracks in Port Moresby on 3 January 1942. This was the first medical unit to arrive in Papua and New Guinea. It initially had no nursing staff.

Later that year, the 2/9th General Hospital from South Australia opened a general hospital 27 km from Port Moresby.

Along the Kokoda Track, stretcher-bearers carried casualties between medical posts. It took eight or 10 Papuan carriers to move each man. Those who could walk, did.

In Alison Pilger's book, Courage, Endurance and Initiative: Medical Evacuation from the Kokoda Track, August–October 1942, Major J. R. Magarey, the Senior Medical Officer of the 2/6th Field Ambulance explains:

It was necessary to be quite ruthless in this respect. Every man who could possibly walk had to; and over and over again men arriving at medical posts could be given only short rests and then had to be pushed on again. The fortitude and cheerfulness shown by the majority of these men was beyond praise, and the feats of endurance performed by some of the wounded, particularly those with wounds of the lower limbs, were almost incredible.

Australian nurses arrived in Papua in October 1942. They worked tirelessly across hospitals and clearing stations, often with the threat of air raids. Learn more about these women at war.

Many of the wounded were sent home on hospital ships, such as the Centaur. In the early hours of 14 May, the Japanese torpedoed the ship. It sank in minutes with the men of the 2/12 Australian Field Ambulance on board. Of the 268 lives lost, there were 18 doctors and 11 nurses. Only 15 men of the 195-strong 2/12 Field Ambulance survived.

Sister Ellen Savage was the only nurse among the 64 survivors.

My cabin mate, Myrle Moston and myself, were awakened by two terrific explosions … We rushed to the porthole, looked out, and saw the ship ablaze.

There is no doubt that the geography, climate and infrastructure of Papua and New Guinea created logistical challenges for both the Allied and Japanese forces.

The great problem of warfare in the Pacific is to move forces into contact and maintain them. Victory is dependent upon solution to the logistic problem.

-General Douglas MacArthur, Supreme Commander of Allied Forces in the Southwest Pacific Area.