The 'Battle of Kaiapit' was a small-scale battle fought between Australian and Japanese forces in New Guinea during the Markham and Ramu Valley/Finisterre Range campaign (19/20 September 1943).

Following their air landing at Nadzab and their sea landing at Lae, the Allies attempted to exploit their success with an advance into the upper reaches of the Markham river valley, starting with Kaiapit. The Japanese intended to use Kaiapit to threaten the Allied position at Nadzab, and to create a diversion providing the Japanese force at Lae time to escape.

The Australian 2/6^th Independent Company flew to the Markham river valley from Port Moresby in 13 USAAF Douglas C-47 Dakota twin-engined transport aircraft, making a difficult landing on a rough airstrip. Unaware that a much larger Japanese force was also headed for Kaiapit, the company attacked the village on 19 September to secure the area in order that the small airstrip could be developed into a larger and better equipped airfield. The company then held it against a strong counterattack. During two days of fighting the Australians defeated a larger Japanese force while suffering relatively few losses.

The Australian victory at Kaiapit made it possible for Major General G. A. Vasey’s Australian 7^th Division to be flown into the upper Markham river valley, which accomplished the 7^th Division’s primary mission of depriving the Japanese of the possibility of threatening Lae or Nadzab, where a major air base was being developed. The victory also led to the capture of the entire Ramu river valley, which provided for the establishment of new forward fighter airstrips for the further prosecution of the air war against the Japanese.

The Markham river valley is part of a flat, elongated depression varying from 5 to 20 miles (8 to 32 km) in width cutting through the otherwise mountainous terrain of New Guinea’s interior, and extending from the mouth of the Markham river near the port of Lae, to that of the Ramu river 370 miles (600 km) away. The two rivers flow in opposite directions, separated by an invisible divide about 80 miles (130 km) from Lae. The area is flat and suitable for airstrips, although it is cut by the many tributaries of the two main rivers. Between the Ramu river valley and Madang on the north coast lies the rugged Finisterre mountain range.

Following the landing at Nadzab, General Sir Thomas Blamey, the Allied Land Forces commander, intended to exploit this success with an advance into the upper Markham river valley, which would protect Nadzab from Japanese ground attack, and also serve as a jumping off point for an overland advance into the Ramu river valley to capture additional airfield sites. On 16 September 1943, the day on which the Allies retook Lae, Lieutenant General Sir Edmund Herring, commander of I Corps, Vasey, commander of the 7^th Division, and Major General Ennis C. Whitehead, commander of the Advanced Echelon, US 5^th Army Air Force, met at the last’s headquarters. Whitehead wanted the establishment of fighter airstrips in the Kaiapit area by 1 November in order to bring his short-range fighters within range of the major Japanese base at Wewak. The 7^th Division’s mission was to prevent the Japanese at Madang from using the Markham and Ramu river valleys to threaten Lae or Nadzab. Vasey and Herring considered both an overland operation to capture Dumpu and an airborne operation using paratroopers of the US Army’s 503^rd Parachute Infantry. Blamey did not agree with their idea of capturing Dumpu first, insisting that Kaiapit be taken beforehand.

Until a road could be opened from Lae, the Kaiapit area could be supplied only by air and the number of transport aircraft was severely limited. Even the aerial delivery of an airborne engineer aviation battalion to improve the airstrip would have involved taking aircraft away from operations supporting the 7^th Division at Nadzab. Moreover, Whitehead warned that he could not guarantee adequate air support for the simultaneous support of the Kaiapit area and the forthcoming 'Postern' operation to take Finschhafen. However, Herring calculated that the 7^th Division had sufficient reserves at Nadzab to allow maintenance flights to be suspended for a week or so after the capture of Kaiapit, and therefore planned to seize Kaiapit with an overland advance from Nadzab by independent companies, the Papuan Infantry Battalion, and the Brigadier Ivan N. Dougherty’s 21^st Brigade of the 7^th Division.

The commander of the US 5^th Army Air Force, Lieutenant General George C. Kenney later recalled that Colonel David W. Hutchison, who had been the air task force commander at Marilinan and had moved over to Nadzab to take charge of air activities there, was told to work out the problem with Vasey: 'I didn’t care how it was done but I wanted a good forward airdrome about a hundred miles further up the Markham Valley. Hutchison and Vasey were a natural team. They both knew what I wanted and Vasey not only believed that the air force could perform miracles but that the 7^th Division and the Fifth Air Force working together could do anything.'

The airstrip at Kaiapit was reconnoitred on 11 September by the RAAF’s No. 4 Squadron, which reported that it was apparently in good condition, with the kunai grass recently cut. An American pilot, Lieutenant Everette E. Frazier, selected a burned-off level area near the Leron river, not far from Kaiapit, and landed in a Piper L-4 Cub single-engined light aeroplane, and decided that it would be possible to land C-47 aircraft there. On 16 September, Hutchison approved the site for C-47 aircraft to land.

The 2/6^th Independent Company arrived in Port Moresby from Australia on 2 August. The unit had fought in Papua during 1942 in the 'Battle of Buna-Gona' and had since undertaken intensive training in Queensland. The company was under the command of Captain Gordon King, who had been its second in command at Buna. King received a warning order on 12 September, alerting him to prepare for the capture of Kaiapit, and had access to detailed aerial photographs of the area.

At this time, the typical independent company had an establishment strength of 20 officers and 275 other ranks. Larger than a conventional infantry company, it was organised into three platoons, each of three sections, each of which contained two sub-sections. It had considerable firepower: each sub-section had a Bren light machine gun, and the gunner’s two assistants carried rifles and extra 30-round Bren gun magazines. A sniper also carried a rifle, as did one man equipped with rifle grenades. The remaining four or five men each carried an Owen sub-machine gun. Each platoon also had a section of 2-in (51-mm) light mortars. The company was self-supporting, with its own engineer, signals, transport and quartermaster sections. The signals section had a powerful but cumbersome Wireless Set No. 11 for communicating with the 7^th Division. Powered by lead-acid batteries which were recharged with petrol generators, its movement required several signallers, and the resulting noise was liable to attract Japanese attention. Each platoon was equipped with the new Army No. 208 Wireless Set. This was a small, portable set developed for the communication needs of units on the move in jungle warfare, but the 2/6^th Independent Company had not had time to work with it operationally.

For three days, the 2/6^th Independent Company prepared to fly from Port Moresby only to be told that its flight had been cancelled as a result of adverse weather. On 17 September, 13 C-47 aircraft of the US 374^th Troop Carrier Group finally took off for Leron. King flew in the lead aeroplane, which was piloted by Captain Frank C. Church, described by Kenney as 'one of Hutchison’s ''hottest'' troop carrier pilots'. As it came in to land, King spotted patrols from the Papuan Infantry Battalion in the area.

One of the transports blew a tyre as it touched down on the rough airstrip; another tried to land on one wheel, but its landing gear collapsed and it made a belly landing. The former was subsequently salvaged, but the latter was a total loss. King despatched patrols that soon located Captain J. A. Chalk’s B Company, Papuan Infantry Battalion, which was operating in the area. That evening Chalk and King received airdropped messages from Vasey instructing them to occupy Kaiapit as soon as possible, and prepare a landing strip for troop-carrying aircraft. Vasey informed them that only small Japanese parties that had escaped from Lae were in the area, and their morale was very low. Vasey flew to Leron on 18 September to meet with King. Vasey’s orders were simple: 'Go to Kaiapit quickly, clean up the Japs and inform division.'

As it happened, Major General Masutaro Nakai, commander of the 20^th Division's infantry group, had ordered a sizeable force (including the 9^th and 10^th Companies of the 78^th Regiment, the 5^th Company of the 80^th Regiment, a heavy machine gun section, a signals section and an engineer company totalling some 500 men) to move to Kaiapit under the command of Major Yonekura Tsuneo . From Kaiapit this force was to threaten the Allied position at Nadzab, creating a diversion to provide the time needed for the Japanese garrison at Lae to escape. The main body left Yokopi in the Finisterre mountain range on 6 September but was delayed by heavy rains that forced the troops to move, soaking wet, through muddy water for much of the way. Only the advance party of this force had reached Kaiapit by 18 September, by which time Lae had already fallen. The main body, moving by night to avoid detection by Allied aircraft, was by this time no further from Kaiapit than King, but had two rivers to cross. Since both parties were heading for the same objective, a clash was inevitable.

King assembled his men at Sangan, about 10 miles (16 km) to the south of Kaiapit, except for one section under Lieutenant E. F. Maxwell which had been sent ahead to scout the village. On the morning of 19 September, King set out for Kaiapit, leaving behind his quartermaster, transport and engineering sections, which would move the stores left at the Leron river first to Sangan and then to Kaiapit on 20 September. He took one section of Papuans with him, leaving Chalk and the rest of his men to escort the native carriers bringing up the stores. King’s men walked for 50 minutes at a time and then rested for 10 minutes. The going was relatively easy insofar as the ground was fairly flat, but the kunai gras, about 6.6 ft (2 m) high, trapped the heat and humidity and the men were heavily loaded with ammunition. The company reached Ragitumkiap, a village close to Kaiapit, at 14.45. While his men had a brief rest, King attempted to contact the large Army No. 11 Wireless Set he had left behind at Sangan, and thence to Vasey back at Nadzab, with the new Army No. 208 Wireless Sets he had brought with him. King found that their range was insufficient, however. He also heard shots being fired in the distance and guessed that Maxwell’s section had been discovered.

The 2/6^th Independent Company formed at 15.15 in the kunai grass about 1,300 yards (1185 m) from Kaiapit. As the company advanced it came under fire from foxholes on the edge of the village. A 2-in (51-mm) mortar was used to destroy a light machine gun position. The foxholes were outflanked and taken out with hand grenades and bayonets, and the Japanese withdrew, leaving behind 30 dead. The Australians lost two men killed and seven wounded, including King, who was lightly wounded.

The company then established a defensive position for the night. While they were doing so, Lieutenant D. B. Stuart, the commander of one of the Papuan platoons, arrived. They had become concerned when radio contact had been lost and he had been sent to find out what was happening. King ordered him to bring the Papuans up from Sangan with extra ammunition and the No. 11 set. At about 17.30, a native appeared with a message for the Japanese commander. The paper was taken from him and he was shot when he tried to escape. Later, a Japanese patrol returned to Kaiapit, unaware that it was now in Australian hands. They were killed when they stumbled across a Bren gun position. Four more Japanese soldiers returned after 00.00, and only one of them escaped.

Yonekura and his men reached Kaiapit after an exhausting night march. Yonekura was aware that the Australians had reached Kaiapit but his main concern was not to be caught in the open by Allied aircraft. Spotting Australian positions in the pre-dawn light, the Japanese column opened fire on the Australians, who replied sporadically as they attempted to conserve their ammunition. Although his men were running short of ammunition, King launched an immediate counterattack, and this took the Japanese by surprise.

Lieutenant Derrick Watson’s C Platoon set out at around 06.15 and advanced to the edge of Village 3, a distance of about 200 yards (185 m), before being pinned by heavy Japanese fire. King then sent Captain Gordon Blainey’s A Platoon round the right flank toward the high ground on Mission Hill which overlooked the battlefield. This had been secured by 07.30. In the meantime, some of the 2/6^th Independent Company’s signallers and headquarters personnel gathered together what ammunition they could, and delivered it to C Platoon at around 07.00. C Platoon then fixed bayonets and continued its advance.

The commander of No. 9 Section of C Platoon, Lieutenant Bob Balderstone, was nicked by a bullet, apparently fired by one of his own men, but continued to lead his section in an advance across 70 yards (64 m) of open ground, and attacked three Japanese machine gun posts with hand grenades. Lieutenant Reg Hallion led his No. 3 Section of A Platoon against the Japanese positions at the base of Mission Hill and was killed in an attack on a machine gun post, but his section captured the position and killed 12 Japanese. By 10.00 the action was over.

After the action, King’s men counted 214 Japanese bodies, and estimated that another 50 or more lay dead in the tall grass. Yonekura was among the dead. The Australians had suffered 14 men killed and 23 wounded. Abandoned Japanese equipment included 19 machine guns, 150 rifles, six grenade throwers and 12 swords.

The 2/6^th Independent Company had won a small but nonetheless significant victory, but now had 23 wounded and was very short of ammunition. Frazier landed on the newly captured airstrip in his L-4 at 12.30 and then rejected the airstrip as unsuitable for C-47 operations. He then supervised the preparation of a new airstrip on better ground near Mission Hill. This was still a difficult approach, as aircraft had to land upwind while avoiding Mission Hill. Although it was not known if the airstrip would be ready, Hutchison flew in for a test landing on the next day, 21 September, at 15.30. He collected the wounded and flew them to Nadzab, and returned an hour later with a load of rations and ammunition. He also brought with him Dougherty, commander of the 21^st Brigade, and his headquarters, who took command of the area. At about 18.00, six more transport aircraft arrived.

Vasey was concerned about the security of the Kaiapit area, as he believed that the Japanese were inclined to continue with a plan once it was in motion. Taking advantage of good flying weather on 22 September, 99 round trips were made between Nadzab and Kaiapit, delivering most of the 2/16^th Battalion and some US engineers. The 2/14^th Battalion and a battery of the 2/4^th Field Regiment arrived on 25 September, and Brigadier K. W. Eather’s 25^th Brigade began to arrive two days later, freeing Dougherty to advance on Dumpu.

Kaiapit did not become an important air base. By the time engineering surveys of the area had been completed, Dougherty’s men had taken Gusap. There, the engineers found a well-drained area with soil conditions suitable for the construction of all-weather airstrips, an unobstructed air approach and a pleasant climate. It was therefore decided to limit construction at the swampy and malarial Kaiapit and concentrate on the development of Gusap, where the US 871^st, 872^nd and 875^th Airborne Aviation Engineer Battalions constructed runways and numerous facilities. Although some equipment was carried on the trek overland, most had to be delivered by air, and nearly all of it was worn out by the time the work had been completed. The first Curtiss P-40 Kittyhawk single-engined fighter squadron began operating from Gusap in November and an all-weather fighter runway was completed in January 1944.

The 2/6^th Independent Company had defeated the vanguard of Nakai’s force and stopped its advance down the Markham river valley. The 'Battle of Kaiapit' accomplished Vasey’s primary mission, for the Japanese could no longer threaten Nadzab. It opened the gate to the Ramu river valley for the 21^st Brigade, provided new forward fighter airstrips for the air war against the Japanese, and validated the Australian army’s new training methods and the organisational emphasis on firepower.

Vasey later told King that 'We were lucky, we were very lucky.' King countered that 'if you’re inferring that what we did was luck, I don’t agree with you sir because I think we weren’t lucky, we were just bloody good.' Vasey replied that what he meant was that he, Vasey, was lucky. He confided to Herring that he felt that he had made a potentially disastrous mistake: 'it is quite wrong to send out a small unit like the 2/6^th Independent Company so far that they cannot be supported.'

The Japanese believed that they had been attacked by 'an Australian force in unexpected strength'. It has been claimed by some Japanese that the mission which the 'Nakai' Detachment achieved was threatening Nadzab so as to draw Allied attention away from the troops escaping from Lae. However, Nakai failed in his intention to hold Kaiapit, while the Allies secured it as a base for future operations. An Australian historian has averred that the 'leisurely Nakai was outwitted by the quick-thinking and aggressive Vasey' In the end, Vasey had moved more rapidly, catching the Japanese off balance. The credit for getting to Kaiapit went first to the USAAF aircrews who managed to make difficult landings on the rough airstrip at Leron. The 2/6^th Independent Company proved to be an ideal unit for the mission, as it combined determined leadership with thorough training and effective firepower.