Charlesworth was promoted to temporary air commodore on 1 August 1944. The following month he was appointed AOC North-Western Area (NWA) in Darwin, Northern Territory, replacing Air Vice Marshal Adrian "King" Cole. By this stage of the war, the Allies were advancing north and the tempo of operations in the Darwin area had decreased. Charlesworth immediately raised concerns regarding No. 80 Wing, which operated three squadrons of Spitfire fighters, warning higher command that its morale could drop if it was not either given a more active role in the war or transferred to southern Australia for rest. By October, the wing had received orders to depart NWA for the forward base of Morotai to join the RAAF's main mobile strike force, First Tactical Air Force; this move would leave Charlesworth with twelve squadrons at his disposal, including one B-24 Liberator heavy bomber unit and three other Spitfire squadrons. In the meantime, NWA supported the assault on Leyte with attacks on enemy ports, oil facilities, and shipping in the Dutch East Indies using Beaufighters, B-25 Mitchells, and Liberators. These operations continued through November–December. In April 1945, Charlesworth sent Mitchells and Liberators against a Japanese convoy led by the cruiser ; the bombers damaged the cruiser, and it was subsequently sunk by Allied submarines. The same month, NWA's Liberators attacked targets in Java in the lead-up to the Battle of Tarakan that commenced on 1 May. By July, Charlesworth's command had been denuded of much of its strength as two of its bomber wings were transferred to First Tactical Air Force.