Last time we spoke about the allied invasion of Balikpapan. In June 1945, the war in the Pacific escalated as American forces, spearheaded by Generals Eichelberger and Krueger, fiercely battled the entrenched Japanese on Luzon. Despite harsh conditions and fierce resistance, the Americans made crucial advances, capturing key positions that rekindled hope for the Filipino people. Concurrently, preparations for the invasion of Balikpapan intensified. The Australian 7th Division assembled for a July 1 amphibious assault against a heavily fortified Japanese defense, known for its formidable coast artillery and entrenched positions. The Australians faced fierce opposition upon landing; however, skilled maneuvering and robust artillery support allowed them to swiftly gain a foothold. As the Australians secured their beachhead, they marked the beginning of a challenging campaign against determined Japanese forces in Balikpapan, setting the stage for further confrontations in the Pacific theater. 

This episode is Victory at Bougainville 

Welcome to the Pacific War Podcast Week by Week, I am your dutiful host Craig Watson. But, before we start I want to also remind you this podcast is only made possible through the efforts of Kings and Generals over at Youtube. Perhaps you want to learn more about world war two? Kings and Generals have an assortment of episodes on world war two and much more  so go give them a look over on Youtube. So please subscribe to Kings and Generals over at Youtube and to continue helping us produce this content please check out www.patreon.com/kingsandgenerals. If you are still hungry for some more history related content, over on my channel, the Pacific War Channel you can find a few videos all the way from the Opium Wars of the 1800’s until the end of the Pacific War in 1945. 

We last left off on Bougainville, by mid-April, Brigadier Heathcote Hammer’s 15th Brigade had commenced its crucial task of relieving Brigadier Field’s weary and battered 7th Brigade. This transition came at a pivotal moment when Brigadier Stevenson’s 11th Brigade successfully secured the Soraken Peninsula, a strategic point on Bougainville's southern coast, while also continuing their efforts to contain enemy forces along the notorious Numa Numa Trail, a crucial supply route for Japanese troops. Supported by reinforcements in artillery and air power, Generals Savige and Bridgeford were optimistic about continuing their limited offensive toward the south. Their immediate objective was to capture the line of the Hongorai River, considered a significant tactical advantage, followed by the Hari River, which would serve as the 15th Brigade’s main aim. On the opposing side, General Kanda had learned a harsh lesson about the ineffectiveness of banzai charges during the fierce fighting at the Battle of Slater’s Knoll. This costly experience prompted him to alter his strategy significantly. He decided to pull his remaining troops back to a defensive perimeter focused around Buin, which is located in the southern region of Bougainville. Here, he reinforced his defenses with garrison troops from Kieta, situated on the eastern side of Bougainville, the Shortlands Islands to the northwest, and the Fauros Islands to the northeast. However, with this concentration of forces not expected to be operational until July, the troops stationed in the forward areas were tasked with executing a critical delaying action in the meantime, buying precious time for reinforcements to arrive.

Meanwhile, on April 17, the Australian 24th Battalion began its advance along the Buin Road, a vital route for both supply and troop movement. Two companies made their way toward Dawe’s Creek, while another company launched an assault against the enemy strongholds at Kindara. Remarkably, they broke through enemy lines the following day, pushing further to Sindou Creek and Umam Creek. Here, they faced multiple sharp counterattacks over the next week, demonstrating the fierce resistance from Japanese forces determined to hold their ground. As patrols moved deeper into the thick jungle on either side of the Buin Road, the struggle became increasingly intense. Each advance was hard-fought, marked by skirmishes that tested the resolve and endurance of the Australian soldiers. Finally, on April 26, the advance resumed in earnest, making rapid gains toward the Hongorai River. The combination of heavy air support and relentless artillery bombardment had effectively dispelled any opposition along the route, allowing the Australians to push forward with renewed vigor.

By May 4, as the 24th Battalion finally approached the banks of the Hongorai River, they encountered significant resistance. However, on the 4th Lieutenant Lawn's platoon was advancing with two tanks and a bulldozer when the crew of the leading tank came to a log across the road and saw movement in the bush. A burst of machine-gun fire from the tank cut the leaves away and revealed the barrel of a field gun. The first round fired from the tank's 2-pounder disabled the enemy gun and the enemy seemed to flee. Farther ahead, however, a mine exploded at the rear of the second tank. It was discovered that it had been exploded with a wire by a Japanese concealed in the bush. Henceforward mines and concealed guns were encountered more and more frequently. They were detected chiefly by the practised eyes of the engineer teams of Major Needham's 15th Field Company who became increasingly skilful. Mechanical detectors were defeated by several sorts of mine employed wooden boxes filled with T.N.T., for example; but their presence was betrayed by protruding fuses, wires, disturbed earth, and confirmed by prodding with a bayonet. As the 24th Battalion neared the Hongorai it became evident that the Japanese intended to make the Australians pay a price for each advance, and that they were willing to trade a field gun for a tank at every opportunity. On the 4th and many later occasions leading tanks were fired on at a range of a few yards by guns cleverly concealed beside the track, but in positions from which the Japanese could not hope to extricate them. In other respects also the Japanese tactics were improving and their striking power was strengthened. Each forward Australian battalion was now under frequent artillery fire, evidently directed by Japanese observers who remained close to the Australian advance, and it was this which was now causing most of the casualties. The shells usually burst in the trees and their fragments were scattered over a wide area with lethal effects. To counter the tanks the Japanese were now establishing their positions not astride the track but about 100 yards from it in places where the tanks could not reach them until a side track had been made.

The Hongorai River, a critical geographical landmark, ran through Bougainville's lush terrain, acting as both a natural barrier and tactical objective. In late April, the 9th Battalion had continued to push forward across the Huio River, a vital waterway that intersected with Japanese defenses. They faced some enemy resistance but managed to clear the Horinu-Rumiki Trail by the end of the month. This narrow, winding path had strategic importance, connecting various units and enabling supplies to move closer to the frontline. On May 3, the 9th Battalion was finally relieved by the 57th/60th Battalion, which, due to its relative inexperience, found progress challenging along the Commando Road a route named after the elite Australian commandos who often operated in this area. Their inexperience in facing seasoned Japanese troops led to slower advances in the crucial days that followed.

Meanwhile, the 2/8th Commando Squadron had been conducting deep reconnaissance patrols towards the Hari River and along the Tiger Road, determined to discover the extent of Japanese defenses south of the Hongorai. The Tiger Road, notorious for its rugged conditions, was pivotal for troop movements in the region. On May 5, the 24th Battalion, now bolstered by a newly assigned tank squadron, resumed its advance with renewed determination. However, they were once again halted by fierce defenders who launched a strong yet costly counterattack the following morning. This desperate but valiant effort by the Japanese troops resulted in significant casualties and demonstrated their resolve to maintain control of the Hongorai line. Subsequently, the Japanese forces ultimately abandoned their positions along the Hongorai during the night. Finally, on May 7, the Australians reached the Hongorai River, marking a significant milestone in their campaign. At that moment, the 57th/60th Battalion was securing a crucial crossing over the Hongorai on the Commando Road, enabling further advances into enemy territory.

With the next objective focused on the line stretching from the Hari River to Monoitu and Kapana, Brigadier Hammer’s battalions shifted their tactics for the second and third weeks of May. They undertook deep patrols into Japanese-occupied territory, gathering vital intelligence while also seeking to harass the enemy and disrupt their operations. Additionally, the commandos maintained their patrols along the challenging Tiger Road and established a new patrol base further north at Monorei. This base would serve as a critical outpost for monitoring enemy movements and launching further operations. Meanwhile, the 58th/59th Battalion explored the rugged areas south of the Buin Road, successfully clearing the Aitara Mission. This mission played a crucial role in their broader strategies, as it prepared them to execute a wide flanking maneuver aimed at cutting the road east of the Hongorai, further encircling Japanese forces.

To support the advancing Australian forces, New Zealand aircraft launched significant attacks on Japanese concentrations positioned along the Buin and Commando Roads. On May 17, the 57th/60t