Battle of the Coconut Grove

In early November, US forces had landed around Cape Torokina and established a beachhead, as part of Allied efforts to advance towards the main Japanese base around Rabaul, the isolation and reduction of which was a key objective of Operation Cartwheel. A Japanese counter landing at Koromokina Lagoon was defeated in the days following the US landing, and the beachhead was subsequently secured. Following this, a blocking force was pushed forward towards the Piva Trail, a key avenue of approach towards Cape Torokina, to defend the narrow beachhead while further supplies and reinforcements were landed. The Japanese commander on Bougainville, Lieutenant General Harukichi Hyakutake, ordered the 23rd Infantry Regiment to advance towards Cape Torokina from the main Japanese position around Buin. Heavy fighting subsequently took place during the Battle for Piva Trail as the Japanese advancing from Buin clashed with the Marine blocking force. The battle resulted in the capture of Piva by US forces, after which a small reconnaissance party of naval construction personnel, escorted by a force of Marine infantrymen, was sent out in search of a site suitable for an airfield. Led by Commander William Painter, a Civil Engineer Corps officer, the party identified a suitable location about beyond the perimeter, about inland, and they set about preparations for the construction of several landing strips for bomber and fighter aircraft. On 9 November, Painter returned to the main perimeter, and the following day the combat patrol also returned, having clashed with a Japanese patrol. Further patrols were sent up the Piva Trail, advancing past a coconut grove that was near the intersection with the East–West Trail. These patrols failed to locate the Japanese. The swamps in the area impeded supply and slowed movement. As a result, it was initially impossible for US forces to advance the perimeter of their beachhead far enough to cover the proposed airfield site selected by 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. This outpost would then be used to send out patrols to disrupt Japanese forces in the local area. As these preparations were taking place, the Japanese, unbeknownst to the US commanders, had occupied a strong position around the coconut grove. thus enabling the US commander to maintain a company in reserve. ==Battle==

While Company E awaited further orders in the assembly area, the remainder of the 2nd Battalion, 21st Marines was supplied with rations, water and ammunition, and awaited the arrival of the artillery forward observer party. At 07:30 Company E was ordered to advance up the Numa Numa Trail and begin to set up the outpost without the rest of the battalion, and at they 08:00 proceeded up the trail without incident. Around 11:05, when the company had reached a point about south of its objective, it came under heavy fire from a Japanese ambush that included mortars and machine guns, as well as sniper fire from the trees. As casualties mounted, Altman dispatched a runner to find Smoak and inform him of the situation. The runner found Smoak with the rest of the battalion at 12:00. They were about south of the trail junction, having been delayed by the late arrival of the forward observer team. Their progress had been further delayed by the swampy ground which had made it difficult to bring up supplies to the assembly area. In response to the news of the ambush, Smoak led the rest of the battalion down the trail as rapidly as possible 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 Captain William McDonough—to reinforce Company E, while Major Edward Clark's Company H was ordered to provide 81 mm mortar support for the attack. Company F—led by Captain Robert Rapp—less the platoon protecting the wire team, was ordered into reserve and to await orders. The artillery forward observer's party was ordered to move forward under the command of Major Glenn Fissel, the battalion executive officer, to assess the situation and call in artillery concentrations to prevent the Japanese from maneuvering. Throughout the night the Japanese defenders fired their rifles sporadically but made no attempt to assault 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 airstrikes 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, communications were cut at 10:45, delaying the attack. 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 the Marines on their flank and accidentally ran over several men. Two tanks were damaged by anti-tank fire and mines. The remaining tanks were ordered to return to an assembly position in reserve. At this time, it was discovered that the Marines had overrun the Japanese positions, although there were still some defenders alive in the dugouts. Riflemen with grenades quickly dealt with these, and by 14:00 all Japanese resistance had been overcome and patrols returned, reporting no further contact. At 14:15, the advance was resumed, with mopping up operations commencing. However, the Japanese troops managed to successfully break contact and began withdrawing to the east. By 15:30 to 15:45 the Marines had occupied their objective, with a perimeter defense organized for the night. ==Aftermath==

US forces estimated that they had come up against a Japanese force of around company strength. The Japanese positions were very extensive and well organized, with numerous machine gun positions and many dugouts that were deep with good overhead cover. Although a careful count of Japanese dead was not taken, 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 riflemen in trees and spider-holes. Without strong fire support, severe losses would have been sustained by the attacking Marines. This set the conditions for US forces to begin an advance on all fronts commencing on 15 November, 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". A few days after the fighting around the Coconut Grove, the Battle of Piva Forks, the final major action around the Torokina beachhead for 1943, was fought. While minor actions were also fought around Hellzapoppin Ridge and Hill 600A in December, the fighting around Bougainville largely died down until March 1944 when the Japanese launched a large-scale assault on Torokina. ==Citations==