The Battle of Borneo was a successful campaign by Japanese Imperial forces for control of Borneo island and concentrated mainly on the subjugation of the Raj of Sarawak, Brunei, North Borneo, and the western part of Kalimantan that was part of the Dutch East Indies. The Japanese main unit for this mission was the 35th Infantry Brigade led by Major General Kiyotake Kawaguchi. Background In 1941, Borneo was divided between the Dutch East Indies and British protectorates (North Borneo, Sarawak and Brunei) and crown colonies (Labuan). The so-called "White Rajahs", the Brooke family, had ruled Sarawak, on the northwest of Borneo, for almost a century, first as Rajahs under the Sultanate of Brunei (a by then tiny but once powerful state entirely enclosed within the borders of Sarawak), and from 1888 as a protectorate of the British Empire. The northeast of the island comprised North Borneo, since 1882 another British protectorate under the British North Borneo Company. Offshore lay the small British crown colony of Labuan. The rest of the island—collectively known as Kalimantan—was under Dutch control. The Netherlands were invaded by Nazi Germany in 1940. However, Free Dutch forces—mainly the Royal Netherlands Navy and the 85,000-strong Royal Netherlands East Indies Army (KNIL, including a small air service)—fought on, spread throughout the Dutch East Indies, and by December 1941 under an embryonic and somewhat chaotic joint Allied command which became the short-lived American-British-Dutch-Australian Command (ABDACOM). The Tripartite Pact—between the three Axis powers of Germany, Japan and Italy—guaranteed mutual support, and this paid off for Japan in July 1941 when French weakness in the wake of the fall of France to Germany allowed Japan to occupy French Indo-China (now modern Vietnam, Laos and Cambodia). This blocked a supply route for the Kuomintang, against whom Japan had been fighting since 1937, the Second Sino-Japanese War. It also gave Imperial Japan a seaboard facing Sarawak and North Borneo across the China Sea. In December 1941, Japan attacked US possessions in Hawaii and the Philippines, declaring war on the US and finally precipitating Germany's official declaration of war on America, according to the Pact. With its rich petroleum exploitation capacity, for instance at Tarakan, Balikpapan and Banjarmasin, Borneo was a prime target for Japan, and a very poorly guarded one. Chronically short of natural resources, Japan needed an assured supply of fuel to achieve its long-term goal of becoming the major power in the