By January 1943 it was apparent that the six-month Japanese occupation of Papua was about to end...
While the Allies, unsuccessful only on the Sanananda road, were considering how to go about the final reduction of the Japanese fortress, the defenders decided to abandon their defences and break out.
The American front
The remaining uncommitted battalion of 18th Brigade, now with considerable tank, artillery and air support, and with an American regiment to assist, eliminated the last Japanese defences west of Giropa Point by 2 January. On the same day Urbana force took Buna Government Station, ending organised resistance in the Buna area. Just too late the Japanese attempted a counterattack out of Giruwa to rescue their position at Buna. A battalion of infantry was brought down by sea from the Amboga River front for the purpose but Colonel Yazawa, in charge of the operation, gave up the attempt when he saw that Buna was already lost. Some 2700 Japanese had defended the Buna enclave with eleven pieces of artillery. Four hundred men escaped to Sanananda and the remaining 2300 died at Buna. The cost to the Allies was 2870 battle casualties, 913 of them Australian.
The Australian front
The Japanese on the Sanananda road had seen off attacks by three Australian brigades and one American regiment. Now the 18th Brigade and a few tanks were transferred to the Sanananda road after their success at Buna. Together with 2/7th Cavalry Regiment and 36th Battalion yet another attempt was made to reduce the main Japanese position on 12 January. This attack achieved little but a subordinate move, to place a new roadblock even further into the Japanese rear, was a success. For a short period a strange situation prevailed. In the space of two kilometres along the Sanananda causeway, furtherest south there was the main Allied position, then the main Japanese defences and north of that the Huggins roadblock. North of Huggins lay another Japanese position. Last of all and furtherest north was the new Allied roadblock. Each side placed ambushes in the swamps on either side of the causeway to intercept the other's attempts to send food and ammunition to their cut off units.
The Japanese breakout
In every aspect the Japanese situation was deteriorating rapidly in January. The decision came down the chain of command from Tokyo to withdraw Yamagata's remaining 5000 men along the coast, by track and barge, via Salamaua to Lae. The breakout was to begin on 20 January but Colonel Tsukamoto, in command on the Sanananda road, took matters into his own hands. A week early he and his men abandoned their positions and, moving through the swamps, escaped to join the Japanese forces holding Amboga River. The Australians, believing Tsukamoto was retreating towards the coast, advanced on Cape Killerton and Sanananda. This had the effect of tightening the noose around the sole remaining Japanese position at Sanananda. When the breakout took place there on 20 January it was much less successful than Tsukamoto's. Though the Battle of Buna-Gona officially terminated on 22 January there was another two weeks of fighting between small Japanese groups escaping along the coast through the area held by the Australian 14th Brigade at Amboga River.
The Battle of Buna-Gona was the largest and longest battle fought in Papua. It resulted in the ejection from Papua of the Japanese after a six-month residence. Of 13,000 Japanese who fought in the battle 3400 either escaped by sea or gathered at Amboga River and began a long retreat to Lae. The rest were dead. The Australian and American victors had committed 27,000 men, almost half of them Australians, to the Battle of Buna-Gona. Their losses were 6419 killed or wounded. Casualties to illness far exceeded this number.
Animated map of the Battle of Buna-Gona