The Battle of North Borneo took place during the Second World War between Allied and Japanese forces. Part of the wider Borneo campaign of the Pacific War, it was fought between 10 June and 15 August 1945 in North Borneo. The battle involved a series of amphibious landings by Australian forces on various points on the mainland around Brunei Bay and upon islands situated around the bay. Japanese opposition to the landings was sporadic initially, although as the campaign progressed a number of considerable clashes occurred and both sides suffered significant casualties, although major combat was largely restricted to Labuan and around Beaufort. On the mainland, while Allied conventional operations focused largely on the coastal areas around Brunei Bay, guerrilla forces consisting of Dayak tribesmen and small numbers of Allied personnel from the Services Reconnaissance Department fought an unconventional campaign in the interior. The Allies were successful in seizing control of the region. Nevertheless, many of the strategic gains that possession of North Borneo provided were ultimately negated by the sudden conclusion of the war in August 1945.

Sabah is a state of Malaysia located on the northern portion of Borneo, in the region of East Malaysia. Sabah has land borders with the Malaysian state of Sarawak to the southwest and Indonesia's North Kalimantan province to the south. The Federal Territory of Labuan is an island just off Sabah's west coast. Sabah shares maritime borders with Vietnam to the west and the Philippines to the north and east. Kota Kinabalu is the state capital and the economic centre of the state, and the seat of the Sabah State government. Other major towns in Sabah include Sandakan and Tawau. The 2020 census recorded a population of 3,418,785 in the state. It has an equatorial climate with tropical rainforests, abundant with animal and plant species. The state has long mountain ranges on the west side which forms part of the Crocker Range National Park. Kinabatangan River, the second longest river in Malaysia runs through Sabah. The highest point of Sabah, Mount Kinabalu is also the highest point of Malaysia.