withdrawal of Japanese forces from the island in early February 1943. At the same time, Australian and American forces in New Guinea repelled the Japanese land offensive along the Kokoda Track. Going on the offensive, the Allied forces captured Buna–Gona, destroying Japanese forces in that area. The ultimate goal of the Allied counter-offensives in New Guinea and the Solomons was to capture the main Japanese base at Rabaul on New Britain, later codified as Operation Cartwheel, and clear the way for the eventual reconquest of the Philippines. Recognising the threat, the Japanese continued to send land, naval, and aerial reinforcements to the area in an attempt to check the Allied advances. Japanese plans Reviewing the progress of the Battle of Guadalcanal and the Battle of Buna–Gona in December 1942, the Japanese faced the prospect that neither could be held. Accordingly, Imperial General Headquarters decided to take steps to strengthen the Japanese position in the South West Pacific by sending Lieutenant General Jusei Aoki's 20th Division from Korea to Guadalcanal and Lieutenant General Heisuke Abe's 41st Division from China to Rabaul. Lieutenant General Hitoshi Imamura, the commander of the Japanese Eighth Area Army at Rabaul, ordered Lieutenant General Hatazō Adachi's XVIII Army to secure Madang, Wewak and Tuluvu in New Guinea. On 29 December, Adachi ordered the 102nd Infantry Regiment and other units under the command of Major General Toru Okabe, the commander of the infantry group of the 51st Division, to move from Rabaul to Lae and advance inland to capture Wau. After deciding to evacuate Guadalcanal on 4 January, the Japanese switched priorities from the Solomon Islands to New Guinea, and opted to send the 20th and 41st Divisions to Wewak. On 5 January 1943, the convoy, which consisted of five destroyers and five troop transports carrying Okabe's force, set out for Lae from Rabaul. Forewarned by Ultra, United States Army Air Forces (USAAF) and Royal Australian Air Force (RAAF) aircraft spotted, shadowed and attacked the convoy, which was shielded by low clouds and Japanese fighters. The Allies claimed to have shot down 69 Japanese aircraft for the loss of 10 of their own. An RAAF Consolidated PBY Catalina sank the transport . Although destroyers rescued 739 of the 1,100 troops on board, the ship took with it all of Okabe's medical supplies. Another transport, , was so badly damaged at Lae by USAAF North American B-25 Mitchells that