The Japanese had concentrated ten flying regiments, their Fourth Air Army,  at Wewak, far beyond the effective range of Allied fighters.  Unwilling to risk  unescorted heavy bombers , US forces constructed an advance air base at Marilinan, sixty miles southeast of Lae from where  fighters could reach Wewak.  On 17 August 1943, Kenney's airmen struck Wewak and left 100 parked airplanes destroyed on taxiways or damaged in their earthen revetments. A follow-up strike the next morning wrecked 28 more Japanese planes. In just two days the Fourth Air Army lost three-quarters of its aircraft. Temporarily crippled, the Japanese were unable to oppose the first coordinated airborne and amphibious assault in the Pacific that occurred two weeks later.