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.
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 Trails, 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 1,000 yd (910 m), 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.
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 200 yd (180 m) 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 1,200 yd (1,100 m) 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 200 yd (180 m) 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 81 mm (3.19 in) 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 75 yd (69 m) in front of the perimeter, and sent out patrols. At 09:05, airstikes were called in, with 18 TBF Avengers 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 100 yd (91 m) 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.
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 1,000 yd (910 m) on the left (west) flank and about 1,500 yd (1,400 m) 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.