The 'Battle of Wau' was fought between Australian and Japanese forces in New Guinea (29 January/4 February 1943).

In 'Sr', Japanese forces had departed the base area at Rabaul on New Britain island in September 1942, crossed the Solomon Sea and, despite Allied air attacks, successfully reached Lae, where they landed at Salamaua and Lae, the latter lying at the head of the Huon Gulf, on 12 and 16 September respectively. The Japanese troops then advanced overland on Wau, an Australian base that potentially threatened the Japanese positions at Salamaua and Lae. There then developed a race between the Japanese moving overland, hampered by the terrain, and the Australians, moving by air, hampered by the weather. By the time the Japanese reached the Wau area after a trek over the mountains, the Australian defenders had been greatly reinforced by air. In the battle that followed, despite achieving tactical surprise by approaching from an unexpected direction, the Japanese attackers were unable to capture Wau.

Wau is a town in New Guinea at one end of the Wau-Bulolo valley. It had been the site of a gold rush during the 1920s and 1930s, the prospectors reaching the coast at Salamaua by sea and then struggling inland along the so-called 'Black Cat Track'. The prospectors and follow-on miners partially cleared the area and built houses and workshops, and established a water supply and an electricity grid. They also constructed airfields at Wau and Bulolo, and these quickly became the primary means of reaching the Wau-Bulolo valley. Wau airfield was a rough kunai grass airstrip 3,100 ft (945 m) long with a 10% slope in the direction of Mt Kaindi. Aircraft could approach only from the north-east, landing uphill and taking off downhill. The mountain at the end of the runway prevented second attempts at landing and precluded extension of the airstrip. Pilots had to manoeuvre the aircraft under cloud and through dangerous passes, and top land at high speed. This was a practice demanding good visibility, but the weather over the mountains of the Owen Stanley range is characterised by frequent storms, vertical drafts, and mists which rise from the jungle floor. The first landing at Wau was made by Ernest Mustard in a de Havilland D.H.37 on 19 April 1927.

After the start of the Pacific War between Japan and the Allied powers, Wau became an evacuation centre, receiving refugees from Lae and Salamaua. Non-native women and children were evacuated, while men of military age were called up for service in the New Guinea Volunteer Rifles, which was the local militia unit. The civilians were at first evacuated by civilian aircraft, but as the Japanese drew closer, bombing Wau on 23 January 1942, it became too dangerous to fly without fighter escort, which was unavailable. This left some 250 European and Asian men stranded. These refugees made a hazardous journey over the Owen Stanley range on foot by way of Kudjeru and Tekadu to Bulldog, a disused mining settlement where there was an airfield, and thence down the Lakekamu river to the sea.

With the feasibility of the route thus demonstrated, the New Guinea Force, commanded successively by Major General B. M. Morris, from August 1942 Major General S. F. Rowell and from 1 October 1942 Major General E. F. Herring, decided to establish a line of communications to Wau via the Bulldog Track. One platoon of the 1^st Independent Company departed Port Moresby in the schooner Royal Endeavour and traversed the route, joining the men of the New Guinea Volunteer Rifles holding the Wau area. This marked the start of what became 'Kanga' Force on 23 April 1942. On 22 May, the 21^st Troop Carrier Squadron of the US Army Air Forces flew in commandos of the 2/5^th Independent Company to join 'Kanga' Force, and the 2/7^th Independent Company followed in October 1942.

Supplies could be flown into Wau only if fighter cover was available. On 5 September, 12 planeloads of supplies were dropped at Kudjeru. To economise on the use of transport aircraft, which were in short supply, air transport was supplemented by an overland route: supplies were shipped to the mouth of the Lakekamu river in luggers, transported up the river to Bulldog in launches or powered dugout canoes, and then carried over the Bulldog Track by native carriers.

'Kanga' Force achieved one notable success in a raid on Salamaua in June 1942, but 'apart from that they had done little to harass the Japanese at their Salamaua and Lae bases'. However, the force had managed to threaten the Japanese without provoking them into an offensive against Wau at a time when the Allies lacked the resources to reinforce 'Kanga' Force, and they had provided valuable information. Wau occupied an important place in the strategy of General Sir Thomas Blamey, the Australian commander, Allied Land Forces, South-West Pacific Area, who was concurrently commanding the New Guinea Force from Port Moresby. At the time, the Japanese held air superiority over the Solomon Sea, precluding airborne or seaborne operations against the Japanese base at Lae. Blamey therefore decided that he would have to capture Lae with a land campaign. The Bulldog Track would be upgraded to a highway capable of carrying trucks and tanks that could support a division that would advance overland on Lae.

Lieutenant General Hitoshi Imamura, commander of the Japanese 8^th Area Army headquartered in Rabaul, correctly deduced his opposite number’s intentions and the strength of 'Kanga' Force, and decided to head off the threat to Lae. He therefore ordered Lieutenant General Hatazo Adachi’s 18^th Army to secure 'important areas to the west of Lae and Salamaua'. On 29 December 1942, Adachi ordered the 102^nd Regiment and other units under the command of Major General Toru Okabe, commander of the 51^st Division's infantry group, to move from Rabaul to Lae and then immediately advance inland to take Wau with his 'Okabe' Detachment.

Imamura was faced by a resourceful, resolute and aggressive opponent, who also had access to good intelligence. Allied 'Ultra' intelligence, stemming in general from the decryption of intercepted Axis communications and in this particular the reading of Japanese shipping codes. By 3 January 1943, Allied commanders knew about the force that Adachi was planning to send from Rabaul to Lae, although not its ultimate destination. Blamey chose not to wait for this to become clear, but immediately ordered Brigadier M. J. Moten’s 17^th Brigade to move from Milne Bay to Wau on 4 January, Moten was ordered to assume command of 'Kanga' Force and defend Wau.

Lieutenant General George C. Kenney, the commander of the Allied Air Forces, South-West Pacific Area, ordered ordered his bomber commander, Brigadier General K. N. Walker, to use the aircraft of his US V Bomber Command to make a full-scale dawn bombing attack on the shipping in Rabaul harbour before it could depart. Walker demurred on the grounds that his bombers would have difficulty making their rendezvous if they had to leave Port Moresby at night, and instead proposed an attack at 12.00. Kenney acknowledged Walker’s concerns but was insistent, for he preferred bombers out of formation to bombers shot down by the Japanese fighters which would inevitably rise to intercept a daylight attack. Adverse weather precluded any participation by bombers from Australia, so all that was available were the aircraft on hand in Papua, which comprised six Boeing B-17 Flying Fortress and six Consolidated B-24 Liberator four-engined heavy bombers. Despite Kenney’s orders, Walker attacked Rabaul harbour at 12.00 on 5 January, and the bombers encountered both heavy anti-aircraft fire and continuous fighter attacks. The bombers dropped 40 500-lb (227-kg) and 24 1,000-lb (454-kg) bombs from an altitude of 8,500 ft (2590 m). The formation claimed hits on nine ships totalling 50,000 tons. Two B-17 bombers were shot down, including that with Walker on board. Post-war assessment concluded that only one Japanese merchant ship, the 5,833-ton Keifuku Maru had been sunk, and that two other ships had been damaged, as had the destroyer Tachikaze.

On 6 January, the Japanese convoy carrying the 'Okabe' Detachment departed Rabaul for Lae. Forewarned by 'Ultra', USAAF and RAAF aircraft spotted, shadowed and attacked the convoy, which was shielded by low cloud and Japanese fighters. The Allies claimed to have shot down 69 Japanese aircraft for the loss of 10 of their own. A Consolidated Catalina twin-engined flying boat of No. 11 Squadron RAAF delivered a night bombing attack on the convoy and sank the transport Nichiryu Maru. Destroyers rescued 739 of the 1,100 troops on board, but the ship took down with her all of Okabe’s medical supplies. Another transport, Myoko Maru, was so badly damaged at Lae by USAAF North American B-25 Mitchell twin-engined medium bomber that she had to be beached. Even so, the convoy reached Lae on 7 January and landed about 4,000 troops. In all, the Allied air forces had flown 416 sorties.

Between 10 and 16 January, the 'Okabe' Detachment moved down the coast in barges to Salamaua, where it assembled and completed its preparations for the attack on Wau. On 16 January, the Japanese encountered a platoon of the 2/7^th Independent Company under Captain Geoffrey Bowen, and there followed a brief action in which Bowen was killed, and the Australians retreated back to Skindewai. Instead of pursuing them, however, Okabe chose to advance on Wau down an old and little used track through difficult country parallel with the Black Cat Track, and the two sides lost contact. Okabe thereby disguised the strength and objective of his force, and took the Australians by surprise. It was necessary to cross Komiatum hill, advance to Mubo, and then take the track to the west: this route was selected in order to reduce the chance of observation by Allied aircraft in the day as the Japanese hacked their way into the jungle. The hill range to the east of Wau is about 1,500 ft (460 m) high and as such offered no particularly difficulties, but in parts there were no tracks. These had to be prepared without being spotted by Allied aircraft. As the troops had to man-pack their own food, ammunition and equipment, the advance was difficult and took longer than had been anticipated. Eventually the Japanese reached a peak from which they were able to look down on the Wau-Bulolo valley. By this time, however, their food was running short. Pointing at the Wau village, Okabe gave the order to attack: 'We are short of food – let us quickly capture Wau and get food from the enemy!' However, the movement through the dense jungle caused his units to lose touch with each other and the resulting attack was delivered piecemeal, without sufficient preparation.

Meanwhile the 2/6^th Battalion, the first group of the 17^th Brigade, had embarked for Port Moresby on 9 January, and the rest of the Australian force followed over the next two nights. The 2/7^th Battalion departed Milne Bay in the army transport Taroona on 13 January and the 2/5^th in Duntroon during the next day. The prospects of beating the Japanese to Wau did not appear to be good. At this time, there were only 28 Douglas C-47 Dakota twin-engined transport aircraft in New Guinea in the understrength 6^th, 21^st and 33^rd Troop Carrier Squadrons of the US 374^th Troop Carrier Group. These aircraft had to be shared with the Buna-Gona front, so the two combat areas each had an allocation of 14 aircraft, and this worked out as 10 aircraft available per day for each. The Dakota could carry 27 passengers or 10,000 lb (4540 kg) of freight. Moving an infantry battalion required 60 planeloads, and the movement of a brigade group required 361 planeloads. Between 10 and 19 January, the 2/6^th Battalion was flown in from Port Moresby to reinforce 'Kanga' Force. In the process, there were three crashes. Poor flying weather forced many aircraft to return without landing, and Moten was twice forced to return to Port Moresby before finally arriving at Wau on the third attempt. Bad weather continued over the following week, limiting air operations and sometimes precluding them entirely. Part of the 2/5^th Battalion arrived on 27 January.

In the path of the 'Okabe' Detachment was A Company of the 2/6^th Battalion under Captain W. H. Sherlock. Okabe ordered an all-out attack on Sherlock’s position on 28 January. Sherlock’s company was forced from its position and retreated onto a nearby spur. For much of the afternoon, Japanese frontal attacks were repelled by Australian mortar and machine gun fire, and Japanese efforts to infiltrate the company’s positions were defeated by a bayonet attack led by Sherlock in person. By 18.00, Sherlock’s mortar ammunition had run out and his small arms ammunition was running short, while his position was being pasted with mortar rounds and swept by machine gun fire. Sherlock held on through the night and was killed the next day trying to break through the Japanese lines.

The fighting at Buna ended on 23 January, thereby releasing more aircraft to support Wau, and 52 brand-new C-47 transports of the US 317^th Troop Carrier Group had arrived in Australia after their delivery from the USA had been expedited in response to urgent requests by MacArthur. After a quick maintenance check, the new aircraft were flown to Port Moresby to support the 374^th Troop Carrier Group in flying the 17^th Brigade into Wau. This meant that up to 40 aircraft were now available on a daily basis.

On 29 January, 57 planeloads of men, supplies and equipment arrived at Wau, delivering most of the 2/7^th Battalion and the remainder of the 2/5^th Battalion. Although subjected to small arms fire as they landed and unloaded, 40 aircraft made 66 trips on the following day. Their cargo included two dismantled 25-pdr gun/howitzers of the 2/1^st Field Regiment with 688 rounds of ammunition, under the command of Captain R. J. Wise. These were landed in the morning and in action before 12.00, shelling a concentration of 300 Japanese troops between the villages of Wandumi and Kaisenik. The Japanese were also engaged by Bristol Beaufighter twin-engined heavy fighters of the RAAF’s No. 30 Squadron flying in the close air support role. Three Dakota aircraft were damaged when one overshot the runway on landing and crashed into two others. One was repaired, but the other two were total losses. Japanese attacks that day succeeded in reaching the corner of the airstrip but were then forced to fall back under enormous pressure.

On 31 January, 35 aircraft made 71 trips, and 40 aircraft made 53 trips on 1 February delivering reinforcements, including the 2/3^rd Independent Company, that brought the strength of 'Kanga' Force to more than 3,000 men. This total included a company of machine guns of the 7^th Machine Gun Battalion flown in specifically to defend the airfield. By 4 February, Okabe was threatened with encirclement and was forced to order a withdrawal. With all hope of capturing Wau gone, Okabe was ordered to abandon the attempt.

The Japanese attempted to cut off the stream of Allied transports by bombing the Wau airstrip, but it was the rainy season and the Japanese were confronted by the same weather conditions which hampered the Allies. Aircraft which did depart Rabaul were not able to sight the Wau airstrip and returned without accomplishing anything. Not until 6 February was there an aerial engagement. Eight Bell P-39 Airacobra single-engned fighters of the 40^th Fighter Squadron were patrolling at 12,000 ft (33660 m) over Wau, having provided escort for a flight of five Dakota transports, when they sighted 24 Japanese aircraft. Captain Thomas H. Winburn led his P-39 fighters into the attack, claiming 11 Mitsubishi A6M Reisen 'Zero' single-engined fighters and Mitsubishi Ki-21 'Sally' twin-engined medium bombers shot down. Meanwhile, eight Curtiss P-40 Warhawk single-engined fighters of the 7^th Fighter Squadron, also on an escort mission, sighted 12 aircraft bombing the airstrip at Wau. The transports they were escorting turned back while the fighters engaged the Japanese, claiming seven aircraft shot down. At this time, there were four Dakota aircraft on the ground at Wau and another five were circling, waiting to land and one of the latter, commanded by 2^nd Lieutenant Robert M. Schwensen, was shot down and all five crewmen on board were killed. One Dakota on the ground was damaged, and a CAC Wirraway single-engined reconnaissance and light attack aeroplane was destroyed by a bomb blast. The Air Co-Operation Signals hut took a direct hit and three men were killed.

The Advanced Echelon headquarters in Port Moresby of the V Bomber Command, now commanded by Major General Ennis C. Whitehead, ordered three squadrons based there to join the battle. Lockheed P-38 Lightning twin-engined fighters of the 39^th Fighter Squadron engaged a dozen Japanese fighters over Wau, shooting down one of them. A few minutes later, the 9^th Fighter Squadron, which had only recently converted to the P-38, downed another Japanese fighter, while P-40 machines of the 41^st Fighter Squadron surprised six Japanese fighters and shot down three of them. The airmen claimed to have shot down 23 Japanese fighters and a bomber. Australian gunners of the 156^th Light Anti-Aircraft Battery claimed another bomber and two fighters.

Between its creation in May 1942 and 15 February 1943, Kanga Force lost 30 officers and 319 men, including four officers and 48 men of the 2/6^th Battalion. The Australians counted 753 Japanese dead, and the addition of the 361 lost on Nichiryu Maru and numerous airmen puts the number of Japanese deaths at abput 1,200 men.

While the New Guinea Force now wished to pursue the retreating Japanese, logistical difficulties made this impossible. The Japanese also prepared to make another attempt to capture Wau. This time, the plan was to approach from the north, building a road from Markham Point to the Snake river valley. From there the advance would have headed down the valley to Wau. Lieutenant General Hidemitsu Nakano’s 51^st Division was earmarked for the task, this suffered heavy losses en route to New Guinea in the air/sea 'Battle of the Bismarck Sea', which exercised a very strong impression of growing Allied air power on the Japanese. A new plan was therefore devised under which an overland line of communication would e created down the Ramu and Markham river valleys. In June, Adachi was ordered to prepare the capture of Wau. Construction of the road was carried out at enormous hardship to the troops involved, but the road was still incomplete when the Allied landings at Nadzab and Lae caused all work to be suspended. For the Allies, Wau became an important starting point for the Salamaua-Lae campaign.