The balance of forces shifted in December...
Allied air power prevented any Japanese reinforcements landing after the middle of the month while the capacity of the Allied supply line grew. More artillery and some tanks arrived to support the infantry which until now invariably failed when assaulting the Japanese defences alone.
The Australian front
An attack on Gona on 1 December made no gains. Vasey decided to try once more with the only fresh troops available, 39th Battalion. The defenders of Gona could not be cordoned off and left to wither as a new factor had intruded into the situation. No longer able to land reinforcements directly into the Buna-Gona area the Japanese were attempting to build up a force of 2500 men north of Gona at the mouth of the Kumusi River. With them was the new Japanese commander Major General Yamagata Tsuyuo. Yamagata planned to sweep around the Australian flank at Gona and take the recently built Allied airfields at Soputa and Dobodura. Without these the Allies would be unable to supply themselves and would have to retreat.
To keep the Japanese on this new front from approaching Gona, Chaforce, a detached force drawn from 21st Brigade, held the area from north of Gona to the Amboga River. On 8 December the attack on Gona commenced and this time it was successful. The next day Lt Col Ralph Honner of 39th Battalion was able to advise to his brigadier that 'Gona's gone'. Very few of the garrison escaped.
Now the Australians were able to turn their attention to Yamagata in the north. His advanced guard had driven Chaforce back but by mid-December the Australians had again advanced to the Amboga River. Here the front quietened down. The Japanese, unable to land most of the force for their planned offensive, abandoned it and instead decided to transfer the majority of the Amboga force into the Sanananda defences by barge. The Royal Australian Navy attempted to interrupt the Japanese coastal traffic by patrolling Holnicote Bay at night.
On the Sanananda road in December the Japanese efforts to eliminate the Huggins roadblock failed. Inside Huggins a small force of Americans held on. Both sides faced the same problem. As Huggins roadblock cut off the main Japanese position so it in turn cut off Huggins roadblock. The Allies and the Japanese were only intermittently able to get supplies through the swamp to their respective isolated forces. In turn the United States 126th Regiment and the Australian 30th Brigade failed in their attempts to link up with Huggins by overcoming the main Japanese position astride the road.
The American front, December
Harding's attack on Buna in November was the worst of all the Allied failures in that month. He was relieved of command and Lt General Robert Eichelberger, the 1st US Corps commander, came forward to run the American battle. Short of artillery and tanks the Allies were willing to try any expedient to break the Japanese defences. On 5 December five Australian Bren carriers, small unarmoured tracked vehicles, led the American attack. All were knocked out within 20 minutes and the attack stalled.
The only small success on the American front in the first half of December was on their left where Urbana force cut Buna village off from the main Buna defences. The Japanese evacuated the pocket on 14 December.
To break the deadlock on the Buna front 18th Australian Brigade was brought up from Milne Bay in Royal Australian Navy corvettes. By now the attacking infantry would have the support of twenty artillery pieces whose accuracy was improved by the aerial spotting of 4 Squadron, Royal Australian Air Force. Light tanks of 2/6th Armoured Regiment had also arrived. In six days 18th Brigade cut their way through defences that had held up the Allies for six weeks. By the end of December the eastern half of the Buna defences was in Allied hands.
Animated map of the Battle of Buna-Gona
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