The battle of Buna–Gona was part of the New Guinea campaign in the Pacific theatre during World War II. It followed the conclusion of the Kokoda Track campaign and lasted from 16 November 1942 until 22 January 1943. The battle was conducted by Australian and United States forces against the Japanese beachheads at Buna, Sanananda and Gona.
The Japanese forces at the start of the Battle of Buna–Gona had an effective strength of 5,500 or 6,500 after the landing of reinforcements on the night of 18 November 1942. The total force at the start of the battle is estimated at 9,000 and included several hospitals, their patients and labour units from the army and navy. The Japanese defensive positions at Buna, Gona and forward at the Sanananda track junction had been strongly developed before the arrival of the Allied forces. They have been described as some of the strongest encountered by the Allies in the course of the war. They made excellent use of terrain, which limited the tactical possibilities for attackers and consisted of hundreds of bunkers and machine gun emplacements developed in depth.
Many survivors of the Kokoda campaign congregated to the west near the mouth of the Kumusi River and linked up with Japanese reinforcements that were landed there in early December. This force actively threatened the western flank of the Australians at Gona. Sources give the total of Japanese forces deployed to Buna–Gona or operating to the west in the vicinity of the Kumusi and Membare Rivers as between 11,000 and nearly 12,000.
In mid December, there was nearly 10,000 deployed at the beachhead positions. Just before the fall of Sanananda and the battle ended, 1,200 wounded were evacuated by submarine. Estimates indicate a similar number were able to escape overland. Only about 250 prisoners were taken. The remainder, some 7,000 to 8,000, were killed.
Defences
Before the Allied forces arrived on the Buna–Gona coast, Richard K. Sutherland, then major general and chief-of-staff to General Douglas MacArthur, Supreme Commander of Allied Forces in the Southwest Pacific Area, had "glibly" referred to the Japanese coastal fortifications as "hasty field entrenchments." After the battle, Lieutenant General Robert Eichelberger, Commanding General US I Corps, called the Japanese utilisation of terrain "perfect" and "brilliant". Natural obstacles were used to advantage to channel attackers into coordinated fields of fire. The Japanese defensive positions at Buna–Gona have been described as "one of the most impressive defensive networks seen in the entire war." They consisted of hundreds of bunkers and machine gun emplacements. The positions had been skilfully developed in accordance with the principles of defence. They made excellent use of terrain, which limited the tactical possibilities for attackers. The defences were developed in depth. Individual positions were mutually supporting and alternative positions were used to confound attackers.
Maximum use was made of locally available resources. Concrete and steel was also used to a limited extent. A typical structure was revetted with coconut logs, reinforced with 44-gallon (55 US gal) drums filled with earth or concrete. The roof was made from two or three courses of logs, covered with earth. Ammunition boxes filled with earth and used rice bags were also common in construction. Most of the structure was built above ground due to the shallow water table. The complete structure might be above ground level. A large proportion had been constructed well in advance of the battle and were extremely well camouflaged by jungle regrowth which quickly covered them. Entrances were designed to protect the occupants from grenade blasts.
Structures were connected by a system of crawl trenches, with firing positions in between. The bunkers were mainly intended to protect the defenders from artillery and air attack. When the threat lifted, the defenders would disperse to firing positions between the bunkers and emplacements. The War Diary of the 2/6th Independent Company recounts:
The main Japanese position was centred on Sanananda and Giruwa. Defensive positions were located on the coastal flanks at Gona, to the west, and Buna to the east. A further position was located forward, astride the Sanananda–Soputa track, about from the coast. These were a series of posts which, apart from covering the approach to Sanananda, also denied the use of two branch tracks to Cape Killerton. The three outer defensive positions can be considered as being located at the corners of a triangle, while the main position was located at the centre of the base. and map. These positions were each separate but, initially at least, they could be readily resupplied and reinforced from the main position. The outer positions covered the likely approaches to Sanananda–Giruwa while the swamp effectively barred any attempt to by-pass these positions.
The Japanese defenders, while not strong in artillery, nonetheless had at their disposal a variety of pieces. Indicative of this is the artillery that was deployed at Buna. McCarthy records, it consisted of: "several 75-mm naval guns, some 37-mm pom poms, 5 heavy anti-aircraft guns and a few 13-mms". The anti-aircraft pieces were quite capable against light armour. There was a battalion of mountain artillery located around Sanananda–Giruwa and a company at Buna.
Japanese tactics were mainly defensive in nature but included counter-attacks when positions were taken. A notable exception was the attack on 25-pounder gun emplacements of 2/1st Field Regiment near Soputa in the first minutes of 29 December. A charge was exploded in the barrel of one of the guns.
Japanese strength
The positions in the Buna–Gona area were manned by both Japanese Naval and Army units. The Naval units included the 5th Special Landing Party, the equivalent of marines. Forces withdrawing down the Kokoda Track added to the strength of the original garrison. Many survivors of the Kokoda campaign congregated to the west near the mouth of the Kumusi River and linked up with Japanese reinforcements that were landed there in early December. Sources generally quote the Japanese effective strength at the start of the battle as 5,500 or 6,500 after reinforcement on the night of 18 November.
Bullard gives a total strength deployed as approximately 11,000 troops. It suggests but does not unambiguously include forces landed as reinforcements around the Kumusi and Mambrae Rivers that did not actually reach the Buna-Gona garrison. Brien gives the strength of the force as 10,000; however, this may have been derived from a planning figure and not an actual strength statement. McCarthy quotes Japanese sources giving the strength in the coastal area as 11,880. It is unclear whether this figure is the initial strength, the maximum strength or the total strength deployed but in light of Bullard's figure, it is likely the total strength deployed. Attributing this figure to the "coastal area" infers it includes forces landed as reinforcements around the Kumusi and Mambrae Rivers that did not actually join the garrison at the beachheads. Milner gives a total effective strength of 5,500 as of 16 November but notes, "No precise figure can be given for Japanese strength at the beachhead in mid-November." This is based on the interrogation of Lieutenant General Hatazō Adachi at the end of the war. Adachi commanded the 18th Army, of which the Buna-Gona garrison was part. He gave the total strength as 9,000. Milner adjusted for troops Adachi included that were not actually located at the garrison and for approximately 1,800 who were hospitalised. In the effective strength, Milner has also included Army and Navy labourers. McCarthy also reports 1,800 hospitalised at the start of the battle. The Japanese hospital facilities were located in the vicinity of Sanananda. The 67th Line of Communications Hospital was located at Giruwa and another hospital at Cape Killerton. Bullard reports that some hospital patients were deployed in defence of Gona (from a line of communications hospital). Watson and Rohfleisch report that in mid-November, "a Japanese report fixes the enemy force ashore in the Buna area at some 9,000 men". Fitzsimons also reports that there were 9,000 at the beachhead positions as the Allies approached. Sandler reports there were approximately 8,000 at Buna-Gona as the Allies were making their final advance toward the beachheads. Total strength figures will include construction units composed of 'non-combat' troops and those that were hospitalised. Bullard and Milner report that hospitalised Japanese were integrated into the garrison's defences. Condon-Rall and Cowdrey record that American troops were kept in the front lines and that, "to evacuate all those with fever at Buna would have meant immediate victory for the enemy.". Cited in .
Strength at key positions
The position at Buna to the Girua River was held by slightly more than 2,000 defenders, having been reinforced by the III/229th Battalion, landed on 18 November. Milner gives the strength as being, "more than 2,500 troops". Edwards records the strength as 2,500. Sandler gives the force as 3,450. Gona was held by 800–900 defenders. Milner states that the initial strength of 800 had been reinforced by a further 100. In context, this appears to be at or shortly before the Australians made contact with the force garrisoned there.
McCarthy records that the Japanese forces in front of Sanananda numbered about 5,500 including the hospitalised. No date is given but in context of text, this might be mid-December. The Center of Military History publication states, "enemy strength in the Sanananda area was therefore between four and five thousand". No date is given but the context suggests this is at or after mid-December. Bullard reports a resupply from the Mambare River to supply approximately 5,000 men. No date is given but the context suggests this is about the time that Buna fell but before 8 January. It may likely have occurred at about the same time as the reinforcement that arrived just before the new year. Milner records, "General Yamagata had some 5,000 troops at the beachhead (including the sick and wounded), but the men had almost nothing to eat and every Japanese in the area faced death by starvation." Bullard gives the strength immediately prior to the fall as 4,000. This gives a detailed breakdown of the fate of the defenders. However, Bullard gives the standing strength of the garrison at about the same time and on the same page as 5,000. McCarthy reports that the Sanananda-Giruwa garrison was strengthened by 200–300 who escaped from Buna.
Sources appear to treat the defenders on the Sananada Track as part of the defences at Sanananda–Giruwa but this does not appear to be explicitly stated. Captured documents gave the strength holding the Sanananda track position as 1,688. McCarthy records that the Sanananda Track defences were manned by approximately 1,700. Milner reports the force as 1,800.
Reinforcements
McAuley indicates at least 1,200 troops landed from Rabaul on the night of 18 November. McAuley also records a Japanese source as stating that 1,500 were landed to reinforce the Gona area at about this time. Bullard records that approximately 1,500 men were landed at the "Buna anchorage" over the nights of 17 and 18 November. Milner gives this as 1,000, landing on the night of 17 November. This reinforcement increased the effective strength to 6,500. Bullard records the landing at Basabua (just east of Gona) of 800 reinforcements for the South Seas Force on the evening of 21 November. McAuley makes reference to this landing but does not appear to indicate the strength of the force landed.