Battle of the Coconut Grove The Battle of the Coconut Grove was a battle between United States Marine Corps and Imperial Japanese Army forces on Bougainville . The battle took place on 13 – 14 November 1943 during the Bougainville campaign . Background . After the battle of Piva Trail and the capture of Piva , a small party of Construction Battalion , with a covering infantry patrol , led by Commander William Painter , Civil Engineer Corps of United States Naval Reserve reconnaissanced for an airfield site . Finding a suitable area located to the north of the perimeter , they set about preparations for the construction of landing strips . Painter returned to the Marine permiter positions a day in advance of the combat patrol , which made contact with a Japanese patrol on 10 November . Further patrols were undertaken up the Piva Trail , beyond the coconut grove near the East - West Trail junction , which failed to establish contact with the Japanese . Due to tremendous difficulties encountered in movement and supply through the swamps , it was impossible to advance the perimeter of the beachhead far enough to cover the proposed airfield site selected by Commander Painter . It was therefore decided to establish a strong outpost , capable of sustaining itself until the lines could be advanced to include it , at the junction of the Numa Numa and East - West Trail s , in order to avoid a fight for the airfield site should the Japanese occupy it first . On the afternoon of 12 November , General Allen Hal Turnage — commander of the 3rd Marine Division — directed the 21st Marine Regiment to send a company patrol up the Numa Numa Trail at 06 : 30 on 13 November . The patrol was to move up the Numa Numa Trail to its junction with the East - West Trail and reconnoiter each trail for a distance of about , with a view of establishing a strong outpost in the vicinity in the near future with Company E , 21st Marines led by Captain Sidney Altman assigned to the mission . Afterward , further orders came from headquarters that the patrol should be increased in strength to two companies , with a suitable command group and an artillery forward observer team . The mission was modified in that the outpost at the junction of the East - West and Numa Numa Trails was to be established immediately . In view of the importance of his assignment , Colonel Evans Ames — commander of the 21st Marines — sought divisional orders to send the entire 2nd Battalion , which was granted . Orders were issued for the 2nd Battalion , 21st Marines — under the command of Lt . Col . Eustace Smoak — to move Company E out at 06 : 30 on 13 November , and proceed to an assembly area in rear of the front line of the 9th Marine Regiment and awaiting until the remainder of the battalion joined it . Battle . On 13 November , Company E — having cleared its bivouac area at 06 : 30 — proceeded to the assembly area in rear of the 9th Marine Regiment front lines , where it awaited further orders . The remainder of the battalion was supplied with rations , water and ammunition , and awaited the arrival of the artillery forward observer party . At 07 : 30 , Company E was ordered proceed out the Numa Numa Trail and begin to set up the outpost , without the rest of the battalion and at 08 : 00 proceeded up the Numa Numa Trail without incident . When the company had reached a point about south of its objective , it was struck by heavy fire coming from a Japanese ambush at 11 : 05 . A runner was sent to Smoak , informing him of the situation . Company E sustained a number of casualties from mortar fire as well as rifles and machine - gun . Smoak — upon receiving the message from the Company E runner at 12 : 00 — was leading the rest of the battalion about south of the trail junction , having been delayed by the late arrival of the forward observer team and difficulty in supplying his troops in their swampy assembly area . Smoak then led the rest of the battalion down the trail as rapidly as possible in order to provide support to Company E . One platoon of Company F was left behind to provide security for the forward observer ' s wire team . By 12 : 45 , the battalion was to the rear of Company E , whereupon Smoak learned that Company E was pinned down by heavy fire and was taking casualties and reinforcement was needed immediately . The Japanese ambush position was located south of the trail junction . Smoak promptly ordered forward Company G — under the command of Capt . William McDonough — to reinforce Company E , while Company H — led by Maj . Edward Clark — was ordered to provide mortar support for the attack . Company F — led by Capt . Robert Rapp — less the platoon protecting the wire team , was ordered into reserve and await orders . The artillery forward observer ' s party was ordered forward to Company E — under Maj . Glenn Fissel — to make an estimate of the situation and call in artillery concentrations to prevent the Japanese from maneuvering . Upon arrival of the artillery forward observer ' s party in Company E ' s lines , Fissel observed that the greatest volume of fire was coming from the east side of the trail , in the direction of Piva River , promptly calling for an artillery concentration in that area . Receiving conflicting reports Smoak , in order to obtain more accurate information displaced his command post forward into the edge of the coconut grove through which the Numa Numa Trail ran . Fissel was able to make contact with Smoak and advised that Company E needed help immediately . Smoak — after a quick reconnaissance — ordered Company F to pass through Company E , resume the attack , and allow Company E to withdraw , reorganize , and take up a protective position on the battalion ' s right flank . Company G — which had reached a position to the left of Company E — was ordered to hold . Company F began its movement forward , and Company E — finding an opportunity to disengage itself — began a withdrawal , redeploying on the right of the battalion ' s position . Company F failed to make contact with either with Company E nor with Company G . During the withdrawal , Fissel was wounded . Unable to determine the exact locations on the battalion ' s companies , Smoak sent several staff officers to determine the exact positions of his companies . Company F could not be found , and a large gap existed between the right flank of Company G and the left flank of Company E which left the battalion in a precarious position . As a result , Smoak ordered Company E to move forward , contact Company G , and establish a line to protect the battalion ' s front and right flank . In the meantime , Company G was to extend its line to the right in order to tie in with Company E . By 16 : 30 , Smoak decided to dig in for the night , with his companies suffering fairly heavy casualties , Company F was missing and communications with regimental headquarters and the artillery had been broken . At 17 : 00 , the gunnery sergeant of Company F reported in person to the battalion command post . Company F had moved out as ordered from its reserve position to the lines held by Company E , however , had veered too far to the right and had missed Company E entirely . Company F proceeded onward and found itself in a position behind the Japanese lines . It was reported by the gunnery sergeant that Capt . Rapp had found it increasingly difficult to control his Company , suffering some casualties and platoons intermingling and becoming disorganized . The gunnery sergeant was ordered to go back to Company F and guide it back to the battalion position . By 17 : 45 , Company F was back in the battalion lines and had taken a position on the perimeter which was set up for the night . At 18 : 30 , communications were reestablished and the 12th Marine Regiment were ordered to set up positions on the north , east , and west sides of 2nd Battalion , 21st Marines perimeter . The 2nd Marine Raiders Battalion — attached to the 21st Marine Regiment — was directed to protect the supply line from the main line of resistance to the 2nd Battalion , 21st Marines . Colonel Ames ordered Smoak to send out patrols and prepare to attack the Japanese positions in the morning , with tank , artillery , and aircraft support . Throughout the night , sporadic enemy rifle fire occurred , with no attempt to attack the Marine positions . On the morning of 14 November , all companies established outposts about in front of the perimeter , and sent out patrols . At 09 : 05 , airstikes were called in , with 18 TBF Avenger s from VMTB - 143 bombing and strafing the area after artillery marked the target with smoke . Immediately after the airstrike , Company E moved back into its original position in the line . Smoak then ordered an attack , with Company E on the left and Company G on the right while Companies F and H would hold in reserve . The attack was to be a frontal assault , supported by five M3 Stuart tanks of the 2nd Platoon , Company B , 3rd Tank Battalion . The attack was set for 11 : 00 ; however , due to communications being cut at 10 : 45 , the attack was ordered delayed until communications had been re - established . The communications were reestablished at 11 : 15 and the attack proposed at 11 : 55 . The 2nd Battalion , 12th Marine Regiment — in direct support — was to provide a 20 - minute preparation followed by a rolling barrage . After the preparatory barrage , the attack commenced at 11 : 55 . The Japanese immediately reoccupied their positions and opened fire with rifles and machine guns . Several tanks of 3rd Tank Battalion became confused and fired into our own troops , and accidentally ran over several men . Two tanks were damaged by enemy anti - tank fire . Complete loss of control and wild shooting occurred for about five minutes , with Smoak moving forward in person and gave orders to cease fire and to halt the advance . Enemy fire having stopped , Smoak directed all companies to stand fast in the positions where they found themselves and to send out patrols to a distance north of the trail junction . The tanks — except the two damaged by enemy anti - tank weapons — were ordered to return to an assembly position in reserve . At this time , it was discovered that the Marines had overrun the enemy positions , and that some Japanese were still present in dugouts . These were quickly reduced by riflemen with grenades . By 14 : 00 , all enemy resistance had been overcome , and patrols returned reporting no further contact . At 14 : 15 , the advance was resumed , and by 15 : 30 the objective was occupied , with a perimeter defense organized for the night . Aftermath . It was estimated that the Japanese force faced was of company strength . The enemy positions were very extensive and well organized , with numerous well constructed machine gun positions and most of the dugouts were deep with good overhead cover . Although a careful count of enemy dead was not taken , it was estimated that a minimum of 40 Japanese were killed . Six enemy machine guns were captured . The Marine forces lost 20 killed , including five officers , and 39 wounded . The battle paved the way on 15 November for an advance on all fronts , extending the perimeter of the Torokina beachhead to about on the left ( west ) flank and about north in the center , to the inland defense line known as " Dog " . Artillery preparation was later recognized as of prime importance against the Japanese system of defenses , with their well dug - in , concealed , and covered foxholes , equipped with a high percentage of automatic weapons , in turn covered by equally invisible riflemen in trees and spider - holes , it had become evident that severe losses would be sustained by attacking infantry , regardless of the size of the force , unless attacks were preceded by artillery or mortar preparation or bombing or by all three .