structural:reformatting, stylistic:tone
New Guinea Campaign

At the Pacific Military Conference in March 1943, the Joint Chiefs of Staff approved MacArthur's plan for Operation Cartwheel, the advance on Rabaul. MacArthur explained his strategy:

My strategic conception for the Pacific Theater, which I outlined after the Papuan Campaign and have since consistently advocated, contemplates massive strokes against only main strategic objectives, utilizing surprise and air-ground striking power supported and assisted by the fleet. This is the very opposite of what is termed "island hopping" which is the gradual pushing back of the enemy by direct frontal pressure with the consequent heavy casualties which will certainly be involved. Key points must of course be taken but a wise choice of such will obviate the need for storming the mass of islands now in enemy possession. "Island hopping" with extravagant losses and slow progress... is not my idea of how to end the war as soon and as cheaply as possible. New conditions require for solution and new weapons require for maximum application new and imaginative methods. Wars are never won in the past.

Lieutenant General Walter Krueger 's Sixth Army headquarters arrived in SWPA in early 1943 but MacArthur had only three American divisions, and they were tired and depleted from the fighting at the Battle of Buna–Gona and the Battle of Guadalcanal. As a result, "it became obvious that any military offensive in the South-West Pacific in 1943 would have to be carried out mainly by the Australian Army". The offensive began with the landing at Lae by the Australian 9th Division on 4 September 1943. The next day, MacArthur watched the landing at Nadzab by paratroops of the 503rd Parachute Infantry. His B-17 made the trip on three engines because one failed soon after leaving Port Moresby, but he insisted that it fly on to Nadzab. For this, he was awarded the Air Medal.

The Australian 7th and 9th Divisions converged on Lae, which fell on 16 September. MacArthur advanced his timetable, and ordered the 7th to capture Kaiapit and Dumpu, while the 9th mounted an amphibious assault on Finschhafen. Here, the offensive bogged down, partly because MacArthur had based his decision to assault Finschhafen on Willoughby's assessment that there were only 350 Japanese defenders at Finschhafen, when in fact there were nearly 5,000. A furious battle ensued.

In early November, MacArthur's plan for a westward advance along the coast of New Guinea to the Philippines was incorporated into plans for the war against Japan. Three months later, airmen reported no signs of enemy activity in the Admiralty Islands. Although Willoughby did not agree that the islands had been evacuated, MacArthur ordered an amphibious landing there, commencing the Admiralty Islands campaign. He accompanied the assault force aboard the light cruiser Phoenix, the flagship of Vice Admiral Thomas C. Kinkaid, the new commander of the Seventh Fleet, and came ashore seven hours after the first wave of landing craft, for which he was awarded the Bronze Star. It took six weeks of fierce fighting before the 1st Cavalry Division captured the islands.

MacArthur had one of the most powerful PR machines of any Allied general during the war, which made him into an extremely popular war hero with the American people. In late 1943–early 1944, there was a serious effort by the conservative faction in the Republican Party centered in the Midwest to have MacArthur seek the Republican nomination to be the candidate for the presidency in the 1944 election, as they regarded the two men most likely to win the Republican nomination, namely Wendell Willkie and Governor Thomas E. Dewey of New York, as too liberal. For a time, MacArthur, who had long seen himself as a potential president, was in the words of the U.S. historian Gerhard Weinberg "very interested" in running as the Republican candidate in 1944. However, MacArthur's vow to "return" to the Philippines had not been fulfilled in early 1944 and he decided not to run for president until he had liberated the Philippines.

Furthermore, Weinberg had argued that it is probable that Roosevelt, who knew of the "enormous gratuity" MacArthur had accepted from Quezon in 1942, had used his knowledge of this transaction to blackmail MacArthur into not running for president. Finally, despite the best efforts of the conservative Republicans to put MacArthur's name on the ballot, on 4 April 1944, Governor Dewey won such a convincing victory in the Wisconsin primary (regarded as a significant victory given that the Midwest was a stronghold of the conservative Republicans opposed to Dewey) as to ensure that he would win the Republican nomination to be the GOP's candidate for president in 1944.

MacArthur bypassed the Japanese forces at Hansa Bay and Wewak, and assaulted Hollandia and Aitape, which Willoughby reported being lightly defended based on intelligence gathered in the Battle of Sio. MacArthur's bold thrust by going 600 miles up the coast had surprised and confused the Japanese high command, who had not anticipated that MacArthur would take such risks. Although they were out of range of the Fifth Air Force's fighters based in the Ramu Valley, the timing of the operation allowed the aircraft carriers of Nimitz's Pacific Fleet to provide air support.

Though risky, the operation turned out to be another success. MacArthur caught the Japanese off balance and cut off Lieutenant General Hatazō Adachi 's Japanese XVIII Army in the Wewak area. Because the Japanese were not expecting an attack, the garrison was weak, and Allied casualties were correspondingly light. However, the terrain turned out to be less suitable for airbase development than first thought, forcing MacArthur to seek better locations further west. While bypassing Japanese forces had great tactical merit, it had the strategic drawback of tying up Allied troops to contain them. Moreover, Adachi was far from beaten, which he demonstrated in the Battle of Driniumor River.