Operation Cartwheel

Bougainville Counterattack

Preparations

by James Miller, jr.

By March 1944 the Japanese were clearly beaten in the Southeast Area. With air and naval strength gone, the ground troops were stranded, immobilized, incapable of affecting the course of the war. Only at Rabaul were the Japanese strong, and that strength could not be employed unless the Allies chose to attack.

Jumbo Map: Japanese Counterattack on Bougainville (very slow: 211K)

But among the characteristics that made the Japanese a formidable opponent was his refusal to accept defeat even in a hopeless situation. If beaten, he knew it not. Thus it was that Generals Imamura and Hyakutake designed the destruction, in March, of the XIV Corps at Empress Augusta Bay, Bougainville.

(This chapter is based on SOPACBACOM, The Bougainville Campaign, Chs. IV-IX, supplemented by rpts, jnls, and jnl files of XIV Corps, Americal Div, 37th Div, and the principal component units which participated; Maj Gen Oscar W. Griswold, Bougainville: An Experience in jungle Warfare (typescript); ACofS G- 2 XIV Corps, History of the "TA" Operation, Bougainville, March 1944 [21 Apr 441; 8th Area Army Operations, Japanese Monogr No. 110 (OCMH), pp. 106-22; 17th Army Operations, II, Japanese Monogr No. 40 (OCMH), 105-29; Capt. Francis D. Cronin, Under the Southern Cross: The Saga of the Americal Division (Washington: Combat Forces Press, 1951), pp. 14368; Frankel, The 37th Infantry Division in World War II, pp. 141-70; Answers (27 Jul 49) of Gen Kanda [former CG, 6th Div] to questions by Hist Sec G-2 FEC, in Hist Div MIS GHQ FEC, Statements of Japanese Officials on World War II (English Translations), II, 19-31, OCMH.)

Preparations

The Approach

When in late 1943 the Japanese commanders had finally concluded that the invasion of Empress Augusta Bay was actually the Allied main effort at Bougainville, they began making plans for their counterattack. Unfortunately for him, Hyakutake's intelligence estimate was as inaccurate as most other Japanese estimates during World War II. He placed Allied strength at Empress Augusta Bay at about 30,000 of whom 10,000 were supposed to be aircraft ground crews. His figure for General Griswold's total strength was too low by half. Against the XIV Corps he planned to use the main strength of the 17th Army, which consisted principally of General Kanda's 6th Division and several battalions of the 17th Division that Imamura had sent down in November.

Total Japanese strength involved is variously reported as 15,000 to 19,000 men. (ACofS G-2 XIV Corps, History of the "TA" Operation, a careful, conservative study written after the counteroffensive from prisoner-of-war interrogations, captured documents, and G-2 periodic reports and summaries, gives 15,400 men as the total. In 1949 General Kanda, speaking from memory, said there were 19,000 men involved plus about 2,000 sailors. He may have included all troops in rear areas in his figure.)

During the early part of 1944 Japanese engineers built or improved roads, trails, and bridges so that the 17th Army could move from north and south Bougainville to assembly areas in the hills inland from the XIV Corps' perimeter. By mid-February the enemy soldiers were all on their way, and Hyakutake left Erventa to supervise the action himself.

The Japanese had hoped to launch an amphibious assault against the Americans, coupled with an attack from inland. A shortage of landing craft made the amphibious assault impossible, but barges, operating on moonless nights to avoid Allied aircraft and PT boats, transported heavy equipment, including artillery, to a point east of Cape Torokina from where it was laboriously hauled inland to the hills. Packhorses and trucks carried supplies part of the way on the overland routes.

The infantry regiments of the 6th Division advanced along both coasts, the 13th and 23d Infantry Regiments on the West, the 45th Infantry up the east coast to Numa Numa, thence southwest by the Numa Numa Trail. The 17th Division battalions also marched along both coasts from their positions in the north.

Such a move could hardly go unnoticed. Coastwatchers, radio intercepts, long- and short- range ground patrols, interrogation of prisoners and even of a few deserters, Japanese activity near the Fiji outpost at Ibu, interpretation of aerial photographs, and air and naval searches told General Griswold that the Japanese were on the move all over the island, and that attack was imminent. Allied planes regularly bombed all suspected troop movements, bridges, and assembly areas. When the Japanese launched strong attacks at Ibu in midFebruary, the corps commander ordered the Fijians back to the perimeter. Four hundred and fifty Fiji soldiers and two hundred Bougainville natives made their Way to Cape Torokina. Two Fijians were slightly wounded during the withdrawal.

Patrol clashes and fire fights in the hills north and northeast of the XIV Corps' perimeter indicated that the Japanese were concentrating there. Further, Japanese carelessness in safeguarding important documents played into General Griswold's hands. Papers taken from enemy corpses gave him a precise idea of Hyakutake's plan of attack, told him exactly which Japanese units were about to attack him, and gave him the general location of the enemy artillery units. Information about the attack was posted on the American units' bulletin boards.

XIV Corps' Defenses

At the beginning of March the XIV Corps' perimeter was somewhat larger than it had been when Griswold took over. It included, in a horseshoe-shaped line on the inland side, some 23,000 yards of low hills and jungle. The beach frontage totaled 11,000 yards. Depth of the position was about 8,000 yards. (Map 22) The main ground combat elements of the corps were the Americal and 37th Divisions, which numbered about 27,000 men. All together, 62,000 men, including naval units, were attached or assigned to the XIV Corps.

All the infantry regiments were placed on the front lines. A total of twelve rifle battalions held frontages varying from 2,000 to 2,400 yards. Usually each regiment held one battalion in reserve. The 37th Division defended the left (northwest) sector from a point on the beach 5,500 yards northwest of Cape Torokina to the area of Hill 700, about 2,000 yards east of Lake Kathleen. The 148th Infantry, on the division left, and the 129th Infantry, in the center, held low ground. The 145th Infantry, on the right, held Hill 700, the highest ground possessed by the Americans. The Americal Division's line ran from just east of Hill 700, where the 164th Infantry's left flank tied in with the 145th's right, over Hills 608, 309, and 270, then along the west bank of the Torokina River. Near its mouth the line crossed over to the east bank. (The 132d Infantry, Americal Division, had seized this area in an action in January wherein S/Sgt. Jessie R. Drowley fought so valiantly that he was awarded the Medal of Honor. WD GO 73, 6 Sep 44.)

The 182d Infantry, in the division's center, held Hills 3og and 270 on the main perimeter line. The 132d Infantry on the right held low ground. In addition a detachment of the 182d Infantry, plus artillery and mortar observers, maintained an outpost on Hill 260, an eminence which was some distance east of the main line of resistance and overlooked the Torokina River. Griswold had ordered this hill held so that it could be used as an American artillery and mortar observation post, and so that the enemy could not use it to observe American positions.

All units had been developing and strengthening positions on the main line of resistance, which now consisted of rifle pits and earth, log, and sandbag pillboxes, wired in behind double-apron or concertina barbed wire. In front of the wire were minefields. Various devices were employed to give illumination at night: searchlights, either shining directly or reflecting a spread beam off clouds; flares tied in trees and set off by pull wires; flashlights; thermite grenades; and cans full of sand and gasoline. Grenades, with wires attached, were set up as booby traps along obvious approach routes. Oil drums, each with scrap metal packed around a bangalore torpedo, were wired for electrical detonation.

Fields of fire fifty yards or more deep, deep enough to prevent the enemy from throwing hand grenades at the American positions from cover and concealment, had been cleared. Almost all the infantry regiments possessed extra machine guns, and had issued two BAR's to each rifle squad. All regiments had constructed reserve positions. The naval construction battalions, the 3d Marine Defense Battalion, Army engineer units, and others maintained provisional infantry units as part of the corps reserve, which also included the 82d Chemical Battalion, the 754th Tank Battalion, and the 1st Battalion, 24th Infantry. (This unit had served on Bougainville since 30 January, chiefly as a labor battalion. See Ulysses G. Lee, Employment of Negro Troops, a volume in preparation for the series UNITED STATES ARMY IN WORLD WAR II.)

Artillery support for the perimeter, though below American standards, was stronger than the enemy's supporting artillery. The XIV Corps still had neither organic artillery nor an artillery commander. Serving as corps artillery commander was General Kreber, artillery commander of the 37th Division. Under General Kreber's command were the eight (six 105-mm. and two 155-mm.) howitzer battalions organic to the two divisions, plus the provisional corps artillery. This consisted of two 155-mm. gun batteries of the 3d Marine Defense Battalion; four go-mm. antiaircraft batteries of the 251st Antiaircraft Artillery Regiment; and four 90-mm. antiaircraft batteries of the 3d Marine Defense Battalion, of which one, D Battery, 70th Coast Artillery (Antiaircraft) Battalion, was attached from the Army. Gun power of the XIV Corps units was augmented on 3 March when six cannon companies, with 75-mm. pack howitzers, reached Bougainville and joined the infantry regiments.

The XIV Corps' positions were strong, and since he possessed interior lines General Griswold could easily switch his reserve units back and forth. But the positions were not ideal. The corps lacked enough men, by American standards, to hold all the high ground in the vicinity. Beyond the coastal plain the ground rises abruptly from ridge to ridge, each higher than the preceding one, up to the summits of the Crown Prince Range. Thus the Americans on Hills 608 and 700 held positions that were dominated by the higher ground in Japanese hands-Blue Ridge, three thousand yards north of Hill 700, and Hills 1000 and 1111, just southeast of Blue Ridge. These hills gave the enemy an excellent view over all the perimeter except the reverse slopes of the American-held hills.

By 1 March, however, General Griswold was sure that "the perimeter was as well organized as the personnel and the terrain would permit." (Griswold, Bougainville, P. 46.)

More Bougainville Counterattack

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