Beginning in August 1943, Allied intelligence gathering activities began working to identify the disposition of Japanese troops as well as gathering key geographic and hydrographic information. Several parties of US and Australian personnel were landed around Bougainville and the surrounding areas throughout the months preceding the operation. These parties were inserted by a variety of means (motor boat, submarine, or by seaplane) to carry out patrols, study the terrain, and gather intelligence from locals, while aerial reconnaissance was also undertaken to the north and south of Bougainville. Submarines were also employed to survey coastal areas and collect hydrographic information.