第一航空戦隊
In January 1942, together with "Akagi" and "Kaga" of the First Carrier Division, the sisters supported the invasion of Rabaul in the Bismarck Archipelago, as the Japanese moved to secure their southern defensive perimeter against attacks from Australia. Aircraft from all four carriers attacked the Australian base at Rabaul on 20 January; the First Carrier Division continued to attack the town while the Fifth Carrier Division moved westwards and attacked Lae and Salamaua in New Guinea. They covered the landings at Rabaul and Kavieng on 23 January before returning to Truk before the end of the month. After the Marshalls–Gilberts raids on 1 February, the Fifth Carrier Division was retained in home waters until mid-March to defend against any American carrier raids on the Home Islands.