 In response to the threat of invasion at Port Moresby , Nos. 11 and 20 Squadrons moved to Bowen , Queensland , on 7 May 1942 . They were soon attacking Japanese targets in Lae , Salamaua and Rabaul . On 27 June , each squadron contributed an aircraft to a four @-@ hour raid over Lae and Salamaua during which , as well as bombs , the RAAF crews dropped beer bottles to disrupt the enemy soldiers ' sleep — the sound they made falling through the air was , according to the official history , " something between a shrill whistle and a scream " . By 1 July , No. 20 Squadron 's strength was six Catalinas and 175 personnel , out of a planned establishment of nine aircraft and 415 personnel . Its prime responsibility in early 1942 was maritime reconnaissance as far as New Guinea , the Solomon Islands , and New Caledonia ; the latter half of the year saw a greater focus on night bombing . Now comprising 252 officers and men , the squadron relocated to Cairns on 11 November 1942 . From Cairns it continued to conduct reconnaissance , anti @-@ submarine and occasional bombing operations over the waters around New Guinea . Between December 1942 and March 1943 , No. 20 Squadron 's aircraft flew a total of 9 @,@ 629 hours and dropped 227 tons of bombs . The squadron 's role changed in June 1943 when it commenced mine @-@ laying operations over the Netherlands East Indies and the Philippines , though it continued to make some bombing raids and supply drops . 
