Balikpapan is a seaport city in East Kalimantan, Indonesia. Located on the east coast of the island of Borneo, the city is the financial center of Kalimantan. Balikpapan is the city with the largest economy in Kalimantan with an estimated 2016 GDP at Rp 73.18 trillion. The city has the third busiest airport in Kalimantan after that in Banjarmasin and Pontianak, namely Sultan Aji Muhammad Sulaiman Sepinggan Airport. Port of Semayang was the second busiest seaport in East Kalimantan, after that in Samarinda.

The Borneo campaign or Second Battle of Borneo was the last major Allied campaign in the South West Pacific Area during World War II to liberate Japanese-held British Borneo and Dutch Borneo. Designated collectively as Operation Oboe, a series of amphibious assaults between 1 May and 21 July 1945 were conducted by the Australian I Corps, under Lieutenant-General Leslie Morshead, against Imperial Japanese forces who had been occupying the island since late 1941 – early 1942. The main Japanese formation on the island was the Thirty-Seventh Army under Lieutenant-General Masao Baba, while the naval garrison was commanded by Vice-Admiral Michiaki Kamada. The Australian ground forces were supported by US and other Allied air and naval forces, with the US providing the bulk of the shipping and logistic support necessary to conduct the operation. The campaign was initially planned to involve six stages, but eventually landings were undertaken at four locations: Tarakan, Labuan, North Borneo and Balikpapan. Guerilla operations were also carried out by Dayak tribesmen and small numbers of Allied personnel in the interior of the island. While major combat operations were concluded by mid-July, localised fighting continued throughout Borneo until the end of the war in August. Initially intended to secure vital airfields and port facilities to support future operations, preparatory bombardment resulted in heavy damage to the island's infrastructure, including its oil production facilities. As a result, the strategic benefits the Allies gained from the campaign were negligible.