"Warrego" was escorting the Dutch ship to Townsville when both ships were recalled to Port Moresby in order to form a convoy to bring forces to Milne Bay. With , "Warrego" escorted "Karsik" and Dutch ship in the first convoy into Milne Bay on 25 June 1942 with Australian troops, American engineers and supplies for the buildup of that base in preparation for port operations and airfield construction. "Warrego", disguised with greenery, stood by as "Karsik" unloaded supplies at an improvised wharf until both sailed for Australia on 28 June. By 11 July, the sloop was back, escorting the Dutch ship with Brigadier John Field and the 7th Brigade Group embarked as Milne Force to protect airfields under construction. By late October "Warrego", , and were assisting the survey vessel in surveying a safe passage for large ships from Milne Bay to Cape Nelson in order to provide large ship support to the Buna campaign that led to "Karsik" delivering tanks to Buna and the supply convoys of Operation Lilliput.