The Tulagi assault force began their landings on Tulagi on 3 May. On 4 May 1942, troopships bearing the South Seas Detachment set sail southward from Rabaul for Port Moresby. This same day US aircraft from "Yorktown" attacked the Tulagi assault force, inflicting heavy damage, but were unsuccessful in preventing the occupation of Tulagi, Gavutu, and Tanambogo islands.