Following the fighting on the Kokoda Trail, Japanese forces occupied a series of well-sited, heavily constructed and cleverly concealed defensive positions in the Buna, Gona and Sanananda area. Australian and United States troops reached the three enclaves in mid-November 1942 but early efforts to take them were unsuccessful and costly. The three positions were sited on high ground, forcing the attackers into waterlogged swampy country.
Like Buna and Gona, the first two enclaves to fall, Sanananda was the scene of fierce and costly fighting. The 16th Australian Brigade made the first attempt. Suffering heavy casualties and widespread illness they made little headway. Further attempts by the 126th American Regiment and the 30th Australian Brigade also failed, leading the Australian commander, Major General George Vasey, to suspend operations until reinforcements arrived from Port Moresby.
Even then the attackers were unable to make significant progress while continuing to suffer heavy casualties. It having become clear that frontal assaults were doomed, attacks on Sanananda were halted while Buna was overcome. Once Buna fell on 2 January Australian and United States units resumed their attack, this time using several different approaches.
Vasey's 18th Brigade began their advance on 12 January making little progress and losing more than 100 men killed or wounded. Despite the attackers' lack of success the Japanese began to withdraw from their forward positions that night. Allied patrols began to report that other Japanese positions had also been abandoned. Fighting continued, however, and a further six days passed before Sanananda village was in Allied hands. The surviving Japanese troops were now surrounded and after three more days of fighting the last organised resistance was overcome. The battle cost some 2,100 Allied casualties and the lives of more than 1,500 Japanese soldiers.