Battle of Hellzapoppin Ridge and Hill 600A The Battle of Hellzapoppin Ridge and Hill 600A was a series of engagements fought in mid - December 1943 on Bougainville between forces of the United States Marine Corps and the Imperial Japanese Army . Although minor in terms of casualties and in comparison to other battles in the campaign , the battle was the last significant action undertaken by the 3rd Marine Division on the island before they were replaced by United States Army soldiers from XIV Corps . It resulted in the capture of the two positions by the Marines with the support of artillery and aircraft , and the withdrawal of the Japanese forces as the American perimeter , which had been established around Torokina , was expanded towards the Torokina River . Prelude . In early November 1943 , the 3rd Marine Division , under Major General Allen H . Turnage , landed at Cape Torokina near Empress Augusta Bay on the western coast of the island . A series of battles were then fought around the beachhead , which was slowly expanded by the Marines out to about by the end of the month . Following the fighting around Piva Forks in late November , plans were drawn up by US commanders to advance towards the Torokina River where a series of high features offered significant defensive advantages that could be exploited in the event of a Japanese counterattack , which US intelligence expected . The general outline of the US plan was to establish a defensive line parallel to the Torokina , along a ridge line that extended to the west from a position in the north known as Hill 1000 to Hill 600A in the south . On 5 December the US advance began and several minor clashes between patrol - sized elements took place . Two days later , Marines from the 3rd Parachute Battalion met resistance along a spur to the west of Eagle Creek , at a position north of the junction of the East – West Trail near Hill 1000 , which later became known to US troops as " Hellzapoppin Ridge " due to its difficult terrain . Documents captured by the advancing Marines indicated that a reinforced company of 235 men from the Japanese 23rd Infantry Regiment was holding the position . The hill , due to its position , threatened the flank of the 3rd Parachute Battalion ' s position and as a result , the Marine commander was forced to readjust his dispositions to place the spur to his front . After consolidating their position and sending out patrols , a number of minor skirmishes took place before the Paramarines launched a company - level attack on the morning of 9 December . Although they managed to break - in to the Japanese position , the Marines were forced back by determined Japanese resistance , having sustained heavy casualties . A flanking maneuver also failed to dislodge the defenders . Late in the day , a company from the 1st Battalion , 21st Marines was sent up to reinforce the Paramarines and the following day the rest of the 21st Marine Regiment , under the command of Evans O . Ames , arrived to take over responsibility for capturing the spur line around Hill 1000 . Battle . Hellzapoppin Ridge . About long and consisting of sheer sides that rose to a sharp crest no more than wide , the spur was heavily vegetated and provided many advantages to defending force . Offering good concealment , this made accurate target identification difficult and reduced the effectiveness of the Marines ' air support as well as the indirect fires offered by their artillery and naval gunfire support . The Japanese defenders were well dug - in on the position , occupying the reverse slope , and having established a series of mutually - supporting positions that were protected with overhead cover and were supported by snipers who were tied - in to the tree tops . Conversely , despite having captured a Japanese map which detailed their positions , lack of familiarity with the terrain and the confined nature of the approaches to it , adversely affected the tactical thinking of the US company commanders , who were unable to concentrate their forces beyond platoon strength in the thick jungle and which consequently took away from them one of their main advantages , firepower . Commencing on 12 December , a series of assaults were attempted by the 21st Marines , utilizing the " partial envelopment " tactic . The well - sited Japanese positions , however , turned any attempt to take the position by an indirect approach into a frontal assault . Although the Japanese fields of fire were limited by the narrowness of the position , they were well concealed and as a result , at least initially , the first that the Marines knew of the location of the Japanese positions was when they were engaged by them at close range . Attempts to reduce the Japanese positions through the use of mortars , artillery and airstrikes were hampered by the dense jungle – the thick vegetation caused tree bursts , while reducing the observation of attacking pilots which resulted in inaccurate strafing and bombing – and as a result it was not until 18 December that a large - scale attack could be launched by the Marines to take the hill . That morning three airstrikes were undertaken , along with an artillery barrage , in preparation for an attack at nightfall . Prior to the attack , a thorough artillery preparation was followed by a fourth airstrike , which was undertaken by six TBF Avenger s from VMTB - 134 , that through close coordination by forward observers on the ground , dropped forty - eight bombs about in front of the US positions . The aircraft also conducted strafing runs of the Japanese positions . A two - pronged attack was then put in by the 1st and 3rd Battalions , 21st Marines . Companies ' A ' and ' C ' from the 1st Battalion attacked the position from the northwest , while Companies ' L ' and ' K ' from the 3rd Battalion attacked from the south . This proved successful as the defenders had been forced from their dug - outs by the earlier artillery fire and air strikes , making them easier targets for the Marines . The previous strikes had also had the effect of clearing some of the vegetation , which made the going easier for the Marines during the attack . In capturing Hellzapoppin Ridge , the Marines lost 12 men killed and 23 wounded . Japanese losses were at least 50 killed . The morning after the attack , the 1st Battalion , 21st Marines exploited the position as far east as the Eagle River – which flowed into the Torokina – where they began work on constructing defensive works to consolidate their position . Hill 600A . Following the capture of Hellzapoppin Ridge , the Marines began sending patrols to the east over the Eagle River towards the Torokina . These lasted for three days and penetrated far behind the Japanese lines , but they did not prove fruitful for the Marines , resulting in no contact to offset the hardships faced in coming to grips with the terrain . Japanese activity during this time was limited to artillery barrages that were brought down largely on the US supply dumps that were located to the southwest around Evansville and which , as a consequence , resulted in only a few casualties . Contact between the two forces was reestablished on 21 December when a Marine patrol was engaged by a force of 14 – 18 Japanese around Hill 600A . Breaking contact , the patrol returned to US lines where the situation was reported and subsequently a detachment from the 2nd Battalion , 21st Marines was detailed with returning to the location and putting in an attack that afternoon . The attack went in at 15 : 45 and for the loss of one man killed and another wounded they were successful in wresting control of the hill from Japanese , who then retired from the position . As the detachment was too small to hold the position against a Japanese counterattack if one was launched , the Marines returned to their main defensive position before the light failed and reported the situation to the 3rd Division command post . Upon receipt of the report , Turnage decided to establish a platoon - sized outpost on the hill and the following morning a force from the 3rd Battalion , 21st Marines , which included heavy weapons support and an artillery forward observer , was sent out to occupy it . The Japanese , however , had returned during the night following the battle and had retaken the position and established themselves firmly . Heavy fire prevented the Marines from advancing and forced them to call back to regimental headquarters for reinforcements . Company ' I ' was sent up , and its commander , misreading the situation and thinking that the Japanese held the crest of the ridge , rather than the foot of its reverse slope , ordered a three - pronged " double envelopment " maneuver , utilizing two elements of his force to flank while the third attacked frontally . With almost no appreciation of the situation or the terrain , the maneuvering elements turned - in to affect the envelopment too soon and consequently moved into the flanks of the platoon that was in contact , rather than the Japanese emplacements . Consequently they too began to take heavy fire and as a result , the American company commander gave the order to withdraw so that an artillery strike could be called down on the Japanese . This too proved to be unsuccessful in forcing the Japanese from the hill and Company ' I ' returned to the main defensive position before sunset . The following day , 23 December , Company ' K ' from the 3rd Battalion , 21st Marines , renewed the attack with a heavy - weapons platoon attached to provide support by fire . Forming up for an attack further south from where Company ' I ' had attacked the day before , one platoon was sent on a reconnaissance along a steep , narrow ridge . Receiving heavy fire , it was forced to fall back and artillery was called in . This had only limited results due to tree bursts ; nevertheless , half an hour later , a second platoon was thrown in and this too was turned back by stiff resistance . Once again indirect fire support was called in , this time lasting only ten minutes but augmented by mortar fires , after which a flanking attack was attempted . This proved unsuccessful and as night fell , Company ' K ' withdrew . The next day , however , Marine patrols found that the Japanese had abandoned the position during the night . Four Marines had been killed and eight wounded in taking the position ; only one Japanese body was found when the position was searched later . Aftermath . By the end of 1943 , although there were about 44 , 000 Americans on the island , a stalemate had developed . While the main Japanese force established itself around Buin in the south of the island with the intention of securing food sources , shortly after the fighting around Hellzapoppin Ridge and Hill 600A the US Marines on Bougainville were relieved by soldiers from the US XIV Corps , which – consisting of only two divisions , the 37th and Americal – adopted a mainly defensive posture around Torokina to protect the four airfields that had been constructed there . As a part of this strategy , outposts were established along the main tracks leading to the port , while Fijian troops patrolled the interior of the island . Between 8 and 25 March 1944 the Japanese commander , Lieutenant General Harukichi Hyakutake , launched an offensive on the American perimeter with 15 , 000 troops , consisting mainly of the 6th Division and two battalions from the 17th , from Buin and Numa Numa . Suffering considerable casualties – over 5 , 000 killed compared to American losses of 263 – the Japanese withdrew back towards the south . From then until the Australian 3rd Division took over responsibility for the island in November 1944 , the Japanese forces – consisting of about 52 , 000 personnel – sought to avoid contact and American forces , while continuing to maintain a presence through fighting patrols and the establishment of outposts in the north and around Numa Numa , generally pursued a strategy of isolating the Japanese garrison .