After landing on the southeastern tip of the island, the single US infantry regiment of three battalions assigned to the operation undertook a two-pronged advance up the eastern and western coasts.

After heavy fighting, the defending Japanese were pushed into a pocket on the northern coast around the Stima Peninsula from where they were evacuated by barge to Kolombangara on 20–21 September.

Efforts to bring forward reinforcements in early August had been disrupted by the loss of three destroyers during the Battle of Vella Gulf; consequently these plans were cancelled and instead the decision made to move the troops from Baanga to Arundel from where they could delay further Allied advances.

[5] In the wake of the campaign on New Georgia, Allied commanders decided to capture Arundel Island so that it could be used to shell the main Japanese troop concentration on Kolombangara, specifically the airfield around Villa.

They then split into two forces that advanced north up the eastern and western coasts through dense jungle and mangrove swamps towards Stima Lagoon in the east and Bustling Point in the west.

On 5 September, the 2nd Battalion attacked heavily fortified Japanese positions around Stima Lagoon that were defended with mines, booby traps, and machine guns.

[7] Supported by artillery batteries firing from Kolombangara, the Japanese resistance proved more intense than US planners had anticipated, and so the 3rd Battalion, 173rd Infantry Regiment was also landed around the lagoon to assist on 5 September.

Having expected only limited combat, the fighting to secure Arundel eventually evolved into a major operation, and the 173rd Infantry Regiment was initially reinforced by the 169th around 8 September.

[7][16] Meanwhile, the Japanese also reinforced the island, dispatching a battalion of Colonel Satoshi Tomonari's 13th Infantry Regiment commencing 8 September, with orders to secure food by attacking US troops around Munda or Bairoko on New Georgia.

The 27th was tasked with clearing Sagekarasa Island and the Bomboe Peninsula, attacking towards the east in an effort to push the Japanese back towards the blocking positions that the 172nd Infantry Regiment was holding.

In response, over the course of the next two nights, the Japanese began evacuating their westernmost staging area and made preparations to reinforce their shrinking perimeter with the remainder of the 13th Infantry Regiment.

[19][18] Exploiting the sound of a heavy downpour to muffle the noise of their engines, five tanks from the 11th Defense Battalion moved into position behind the 27th on the west coast on the night of 16–17 September.

The following morning the five tanks, operating in two waves with infantry support, destroyed a Japanese strongpoint, allowing the front line to advance 500 yards (460 m).

As a result of capturing Arundel, the US commanders managed to secure the airbase around Munda from counterattack or shelling, although it remained under threat from Japanese air attack.

[27] In the aftermath, the fighting continued on Vella Lavella, where the New Zealand 14th Brigade arrived to take over responsibility for the final advance through the coastal areas from US troops.

[31] The next phase of the Allied advance through the Pacific would see them land at Cape Torokina in November 1943 as part of efforts to secure Bougainville, while further actions were undertaken by the New Zealanders in the Treasury Islands and the US Marines on Choiseul.