By August 1943, the Fourth Air Army—which had been formed in June for the
New Guinea campaign—had 200 aircraft, but only 130 of them were operational and ready for flying. This was one third of its full complement of planes and represented an operational strength of 50%. According to Japanese historian Hiroyuki Shindo: "...the major causes of this low operational rate were widespread illness among the aircrews, along with ... the lack of aircraft replacements." Allied personnel started construction of two dummy airfields, relatively close to Japanese infantry positions on the
Huon Peninsula, north of
Lae. Small construction crews created large clouds of dust, to create the impression that major construction was underway. The Japanese responded by frequently bombing the "airfields", and apparently preventing occupation by Allied units. Simultaneously, at
Tsili Tsili, away, the Allies constructed a real airfield and transferred fighter planes there before the Japanese discovered its existence. (However, the Australian official history says the new, secret base was the separate airfield at nearby
Marilinan, from Lae.{{cite book | last = Odgers | first = George | year = 1957 | url = https://www.awm.gov.au/collection/RCDIG1070210/ On 12 August, the Fourth Air Army began to carry out a wave of raids on the Allied air bases at
Mount Hagen,
Bena Bena,
Wau,
Salamaua and elsewhere. Some small Allied raids were undertaken against Wewak. ==Attacks==