The 'Bombing of Wewak' was a series of US air raids by aircraft of Lieutenant General George C. Kenney’s US 5^th Army Air Force against the major air base of the Imperial Japanese army air force at Wewak on the mainland of New Guinea (17/21 August 1943).

The four raids, over a five-day period, were a decisive Allied victory; Lieutenant General Kumaichi Teramoto’s 4^th Air Army lost about 170 aircraft on the ground and in the air, reducing its operational strength to about 30 aircraft, and the USAAF lost a mere 10 machines.

By August 1943, during the Allies' 'Campaign in Eastern New Guinea', the 4^th Air Army, which had been formed in June for the New Guinea campaign, had 200 aircraft, of which only 130 were operational. This was one-third of the air army’s full complement of aircraft and represented an operational strength of 50%. The major causes of this low operational rate seem to have been widespread illness among the aircrews, together with the lack of aircraft replacements. Even so, the Japanese aircraft included modern fighters such as the single-engined Nakajima Ki-43 Hayabusa 'Oscar', the new inline-engined Kawasaki Ki-61 Hien 'Tony', and the twin-engined Kawasaki Ki-45 Toryu 'Nick' ground attack warplane and night-fighter.

During the Australian and US armies' 'Campaign in Eastern New Guinea', directed primarily at the seizure of Lae, the 4^th Air Army moved a large number of aircraft out of range of Allied fighters to a cluster of airfields near Wewak, some 400 miles (655 km) to the west of the Huon peninsula. Escort fighters operating from current Allied bases lacked the range to reach Wewak, and the Allies considered major long-range raids by unescorted heavy bombers to be at risk of heavy losses.

Kenney, the Allied air commander in the South-West Pacific Area, devised a plan for a major attack on Wewak. Allied personnel started construction of two dummy airfields, relatively close to Japanese infantry positions on the Huon peninsula, to the north of Lae. Small construction crews created large clouds of dust, to create the impression that major construction was under way. The Japanese responded by frequently bombing these 'airfields' and apparently preventing their occupation by Allied units. Simultaneously, at Tsili Tsili, 50 miles (80 km) away, the Allies constructed a real airfield and moved fighters onto it before the Japanese discovered its existence. (The Australian official history claims that the new, secret base was the separate airfield at nearby Marilinan, 40 miles/64 km from Lae.)

On 12 August, the 4^th Air Army began to carry out a wave of raids on the Allied air bases at Mt Hagen, Bena Bena, Wau, Salamaua and elsewhere. Some small Allied raids were undertaken against Wewak.

On 17 August, 47 Consolidated B-24 Liberator and Boeing B-17 Flying Fortress four-engined heavy bombers made a pre-dawn attack on the main base at Wewak and satellite airfields at Boram, Dagua and But. The attacking bombers found Japanese aircraft parked wing-tip to wing-tip on runways. At Boram, 60 Japanese aircraft were being readied for flight. Some attempted to take off but were destroyed in the process. At 09.00, more than 30 North American B-25 Mitchell twin-engined medium bombers, escorted by more than 80 Lockheed P-38 Lightning twin-engined fighters made strafing attacks on Boram, Wewak and Dagua.

Another attack on the airfields was despatched on the morning of 18 August to strafe and bomb the fields from low altitude. The 3^rd Attack Group was assigned to attack Wewak and Boram airfields, while the 38^th Bomb Group was sent farther to the west to attack Dagua and But airfields. Each of the 62 bombers was loaded with 12 clusters of three 23-lb (10-kg) 'para-frag' bombs. B-24 bombers of the 90^th Bomb Group attacked Wewak from high altitude, while 53 B-25 bombers succeeded in reaching Wewak and attacked the airfields again. Only three US aircraft were lost in the raids.

The attacks caught the Japanese unprepared. Their New Guinea airfields were inadequate in terms of aircraft concealment in hangars and other shelters, and they relied almost completely on a visual warning system, which did not allow enough time for aircraft on the ground to take-off or be taken under cover. These problems were compounded by the poor quality of runways, a shortage of maintenance staff and a lack of heavy equipment at forward bases. These problems were not restricted to Wewak and, according to an Australian official historian, during this period at least 50% of the Japanese aircraft lost were destroyed on the ground.

Two additional raids were conducted on 20 and 21 August. The 5^th AAF claimed 20 aircraft destroyed on 20 August, and 70 on the final day, half of them shot down in air combat by escorting P-38 fighters.

According to the 4^th Air Army's numbers, out of 200 Japanese aircraft at the four Wewak area airfields, 174 were put out of action: 54 were shot down, 16 blown up, 57 badly damaged, and 47 slightly damaged. The 4^th Air Army had thus been reduced to an operational strength of about 30 aircraft, and this meant a virtual end to Japanese air operations in New Guinea until replacements had arrived. The Allies could now conduct air operations virtually uncontested as far away as Aitape, whereas previously Madang had been the extent of air operations. The 4^th Air Army recovered to an extent, but never again reached the strength it had possessed in August 1943. The last major air combat between Allied and Japanese aircraft took place on 3 June 1944. The final aerial victories of the New Guinea campaign for the USAAF and Royal Australian Air Force occurred in June 1944, and by that time the 4^th Air Army had ceased to exist.