"Sōryū" and "Hiryū" arrived at Palau on 28 January and waited for the arrival of the carriers "Kaga" and "Akagi". All four carriers departed Palau on 15 February and launched air strikes against Darwin, Australia, four days later. "Sōryū" contributed eighteen B5Ns, eighteen D3As, and nine Zeros to the attack while flying Combat Air Patrols (CAP) over the carriers. Her aircraft attacked the ships in port and its facilities, sinking or setting on fire eight ships and causing three others to be beached lest they sink. The Zeros destroyed a single Consolidated PBY Catalina flying boat; one D3A was lost. The Japanese aircraft spotted a ship on the return trip but had expended all their ordnance and had to be rearmed and refueled before they could attack the vessel. Several hours later, nine of "Sōryū"s D3As located and bombed an American supply ship of , "Don Isidro", hitting her five times but failing to sink her. "Sōryū" and the other carriers arrived at Staring Bay on Celebes Island on 21 February to resupply and rest before departing four days later to support the invasion of Java. On 1 March 1942, the ship's D3As damaged the destroyer badly enough for her to be caught and sunk by Japanese cruisers. Later that day the dive bombers sank the oil tanker . The four carriers launched an airstrike of 180 aircraft against Tjilatjep on 5 March, sinking five small ships, damaging another nine badly enough that they had to be scuttled, and set the town on fire. Two days later they attacked Christmas Island before returning to Staring Bay on 11 March to resupply and train for the impending Indian Ocean raid. This raid was intended to secure newly conquered Burma, Malaya, and the Dutch East Indies against Allied attack by destroying base facilities and forces in the eastern Indian Ocean.