the one good line of approach, and its base was anchored on strongpoints covering the coastal trail between Cape Killerton to the west and Tarakena to the east. Gona was a flank position to the northwest of the main stronghold and could be reached from Soputa by a trail west of the road.
A group of mutually supporting positions at the apex on the Soputa-Sanananda Road covered the junction with the road of a branch trail to Cape Killerton. A half mile to the north was another group of positions where a second trail branched off toward Cape Killerton, and a half mile still further north was a third group of positions. Each defensive position consisted of a single ring of bunkers similar to those found at Buna, connected by fire and communication trenches and thus constituting a perimeter. Many of these perimeters were flanked by swamps and all were well concealed in the dense jungle.
Within the fortified area were concentrated some 3,000 survivors of the unsuccessful attack on Port Moresby, together with reinforcements which arrived by sea. Two of these units which had been decimated in the retreat across the Owen Stanley Mountains could be identified only tentatively: the Kusonose Butai and the Yokoyama Engineers. A third was definitely established as the Yasawa Butai. It consisted of 3 battalions of the 41st Infantry; the 1st Battalion was stationed at Gona, while the 2d and 3d were on the Soputa-Sanananda Road near its junction with the Killerton trail. On 20 November about half of the enemy troops were in positions along the road north of Soputa while the rest were on the coast.
Reinforcements arrived during the first 2 weeks of December. A detachment of the Yamagata Brigade, numbering less than 1,000 and consisting of the Brigade Headquarters, the 3d Battalion of the 170th Infantry, and 1 battery of mountain artillery, landed north of Gona during the night of 1–2 December. A second detachment of the same brigade, also less than 1,000 in number, landed near the mouth of the Mambare River on the night of 12–13 December. The total enemy strength in the Sanananda area was therefore between four and five thousand, at least twice the strength of the Buna garrison.
The Sanananda operation was conducted at first by the Australian units which had pushed the Japanese back across the Owen Stanley Mountains. But these units were too exhausted and too few to crack
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