During the Dutch East Indies campaign of World War II, the Japanese invaded Borneo. Immediately after the capture of Balikpapan on January 26, 1942, the 56th Mixed Infantry Group was ordered to complete the occupation of Dutch Borneo by invading Bandjermasin, its capital. During the Battle of Balikpapan and also after the occupation of the city, all efforts were made to gather information from Japanese residents, natives and prisoners of war. Reconnaissance flights in the area were carried out by naval air units. It was necessary to capture Bandjermasin, as soon as possible, to secure its airfield for combat aircraft scheduled to participate in the Java Operation.