These troops were commanded by Maj. Gen. Oda, succeeding General Horii, who had been drowned in the Kumusi River while retreating from the attack on Port Moresby. In addition to the infantry already mentioned, which numbered about 1,165, he had at Buna a number of other elements: a heavy antiaircraft battery which was tentatively identified as the 73d Independent Unit, with a minimum strength of 100; a battery of mountain artillery believed to be from the 3d Battalion, 55th Field Artillery, and numbering at least 100 men; about 100 men remaining from the 144th Infantry, which had been decimated in the Port Morsby expedition; some 300 miscellaneous troops, including engineer, medical, signal, and supply personnel; about 400 Japanese, Formosan, and Korean laborers of the 14th and 15th Construction Units. The Japanese force at Buna thus totaled about 2,200, of which some 1,800 were combat troops. Only the remnant of the 144th Infantry had taken part in the disastrous retreat over the Owen Stanley Mountains; the rest were fresh and ready for battle.
Our troops approached Buna completely ignorant of the defenses which faced them. They found the enemy forces established in almost impregnable defensive works, which baffled the earlier attackers and left them uncertain of the exact location of their foes. They first had to find out just where the Japanese were and then solve the problem of how to drive them from their fortifications.
The defenses consisted essentially of a network of mutually supporting bunkers, organized in depth. The 32d Division at Buna was the first American unit to meet and conquer this type of defense. At Munda, Salamaua, and all other points in the Southwest Pacific Area where we have since encountered prepared Japanese positions, the experience gained at Buna has proved valuable.
Dugouts are not feasible in the Buna area because the water table is too close to the surface. The Japanese bunkers were, therefore, almost entirely above ground. The base of the bunker was a shallow trench, up to 40 feet in length for the larger bunkers, and 6 to 10 feet for the smaller. A framework of columns and beams was set up, the walls were revetted with coconut logs ranging up to 1½ feet in thickness, and a ceiling of two or three courses of such logs was laid on top. Not content with this construction, the enemy reinforced the wall, using steel oil drums and ammunition boxes filled with sand, as well as log
14
