Second World War at Sea: Java Sea
Conquest of Borneo
By Mike Bennighof, Ph.D.
January 2024

Japan’s decision to make war on the United States and Great Britain arose from several factors, not least of them the August 1941 American embargo on oil exports to Japan. Japan drew more than 80 percent of her oil from the United States, and the Dutch rulers of the East Indies were not willing or able to sell enough oil to Japan to make up the difference.

The oil-rich island of Borneo, on the northern fringe of the East Indies just south of the American-held Philippines, held the answer to Japan’s needs. With the interior mostly covered in jungle, Borneo’s towns, such as they were, clustered on the coastline. The north coast hosted the White Rajahs of Sarawak, the Sultanate of Brunei, and British North Borneo, all of them British protectorates. The remainder, about two-thirds of the island, came under the rule of the Dutch East Indies. All of these colonial territories sported large, productive oilfields, and none of them boasted much in the way of defenses.

The British had dispatched an Indian battalion to Sarawak, to supplement the White Rajah’s small army, the Sarawak Rangers. In all, British and Sarawakian forces numbered about 2,500 men; Brunei and North Borneo had several hundred police each but no armed forces. Sarawak’s Rajah Vyner Brooke had made some preparations for defense, building hidden airstrips in the jungle and filling oil wells with concrete to deny them to the invaders and donating his private yacht to the Royal Navy. But the British sent no aircraft, and the strips eventually fell into Japanese hands.

Japanese paratroopers on their way to Borneo.

The Dutch had little more force, with a few thousand men of the Royal Netherlands East Indies Army (KNIL) and hastily-raised militia. On 25 November 1941 the Dutch added a small air contingent, with five Brewster Buffalo fighters and ten Martin B10 bombers. The Dutch had built their own secret airfield, just south of the border with Sarawak, which put their bombers within range of potential Japanese landing zones on the northern coast. Dutch naval commander Conrad Helfrich intended to conduct an aggressive defense, even before the Japanese entered Dutch waters or declared war.

The Japanese invasion force would be built around the 35th Infantry Brigade and the Imperial Navy’s Yokosuka Special Naval Landing Force, with a combined total of about 4,500 infantrymen. Landings began on 17 December, and immediately met resistance from Dutch aircraft and submarines. A Dutch flying boat dropped a pair of bombs on the destroyer Shinonome, igniting her magazine. The Fubuki-class Special Type destroyer exploded and sank, taking all 197 of her crew with her (the Japanese would claim that she struck a mine). The Dutch submarine K-XVI sank the Fubuki-class boat Sagiri; another magazine explosion took 121 sailors with the destroyer. Submarine K-XIV infiltrated a troop convoy and sank two of its transports.

By late December the Japanese had discovered the secret Dutch airfield and subjected it to repeated attacks, forcing its abandonment. The remaining British and Dutch troops withdrew southward, leaving the protectorates in Japanese hands. But the Dutch segment remained to be conquered.

That effort began as soon as the ports and airfields in the north had been secured, and the transports could be made ready for the next phase. There was also the formality of declaring war on the Netherlands; all of the preceding combat had taken place with Japan and the Dutch still legally at peace.

Minesweeper W13. Sunk at Tarakan, her crew helped massacre Dutch prisoners.

The first target would be Tarakan, a small island just off the north-east coast of Borneo boasting abundant oil, held by a battalion of Dutch colonial troops with coastal defense artillery and some air support. The invading Sakaguchi Detachment numbered about 6,000 men drawn mostly from the Army’s 146th Infantry Regiment and the Navy’s 2nd Kure Special Naval Landing Force. The 4th Destroyer Flotilla escorted them, with the light cruiser Naka and ten destroyers, with two seaplane tenders plus a minelayer, submarine chasers and minesweepers rounding out the force. When lookouts spotted the approaching Japanese, the Dutch set the oilfields and storage tanks alight.

By the light of the blazing oil, the Japanese came ashore before dawn on 11 January, and by the following afternoon had subdued the defenders. The Japanese commander warned the naval forces that the coast-defense battery at the south end of the island probably didn’t know of the surrender, but the Japanese ships pressed on into the anchorage anyway and Dutch gunners sank two Japanese minesweepers. When the battery surrendered some hours later, the Japanese massacred the gun crews, killing over three hundred men through forcible drowning and beheading, with the officers tied up and thrown to crocodiles.

The submarine K-X successfully slipped out of Tarakan’s anchorage and escaped, but the minelayer Prins van Oranje encountered the destroyer Yamakaze and sank after an intense but one-sided firefight, taking 102 of her 118 crewmen with her. Dutch aircraft attacked Tarakan Airfield and the ships of the invasion force, but the Japanese kept the airstrip operating.

Balikpapan burns as the Japanese advance.

On the same day that the Japanese attacked Tarakan, naval infantry and paratroopers attacked the Dutch seaplane base and airfields at Manado on the far north-eastern tip of the large island of Celebes, just east of Borneo. Many of the Dutch colonial troops promptly deserted, but the remainder put up spirited resistance before melting away into the jungle to wage guerilla warfare. The Japanese paratroopers suffered 32 dead and 90 wounded; once the airfields had been secured on the 13th, they murdered 15 prisoners: 13 by beheading, and two by torture.

The Allies had formed their ABDA Command (American-British-Dutch-Australian) on 1 January, giving American Admiral Thomas Hart command of all Allied naval forces in the region and stifling Helfrich’s desires to strike immediately and often at the Japanese. A Dutch cruiser-destroyer force off Borneo was pulled back on to defend convoy traffic, in keeping with Hart’s policy of preserving Allied warships.

The important oil center at Balikpapan stood next on the Japanese timetable. Beyond oilfields, Balikpapan boasted huge tank farms, an oil refinery, and a nascent petrochemical industry. And perhaps most importantly, it had airfields that would put Japanese planes within easy range of Java, the political and military center of Dutch power in the East Indies.

Japanese plans assigned Balikpapan to the same land and naval forces that had taken Tarakan; the swift capture of that oil production center allowed the schedule to be moved up. Shizuo Sakaguchi, the invasion force’s commander, sent a delegation of high-ranking Dutch prisoners to Balikpapan with an ultimatum, threatening reprisals against prisoners and civilians alike if the Dutch destroyed the oil facilities. The Dutch commander, Lt. Col. Cornelis van den Hoogenbrand, politely listened to the demand and then immediately ordered demolitions and evacuation of civilians to begin. Hoogenbrand’s engineers had estimated that these would take about three hours; instead, it took three days to thoroughly wreck the facilities, which Sakaguchi had granted the Dutch thanks to his ultimatum.

The Japanese sailed on 21 January, the day after the ultimatum was received. With foreknowledge of the move (again, thanks to Sakaguchi’s gambit), American and Dutch submarines were waiting. The American submarine Sturgeon claimed sinkings of three troop transports, but none of her torpedoes actually exploded. Dutch bombers did sink one transport, but the landings went forward on the 23rd and Hoogenbrand’s garrison soon found itself outmatched.

This time, ABDA naval forces responded. Hart sent his surface action group to attack the Japanese, commanded by Vice Admiral William Glassford. Glassford had two light cruisers and six destroyers, but things soon went wrong. The powerful cruiser Boise hit an uncharted reef, while the older Marblehead suffered a turbine breakdown. Glassford detailed two of the destroyers to accompany the stricken cruisers to Dutch bases on Java, while the remaining four boats pressed on.

Dutch submarine K-XVIII, seen in 1935.

The Japanese mistook the American destroyers for Japanese boats, and did not challenge their entry into Balikpapan’s harbor, where the Dutch submarine K-XVIII had just sunk a Japanese transport. The Americans loosed their torpedoes at the helpless transports, sinking three of them (including one loaded with ammunition and another with mines and depth charges) before escaping untouched, with the Japanese still hunting for K-XVIII and attributing the explosions and chaos to enemy submarines.

That success did not stop the invasion. The Dutch tried to melt away into the jungles, but most of the colonial soldiers deserted instead. American B-17 bombers made continual raids on Balikpapan, and when Japanese Navy Zero fighters began to operate from the city’s airfields, the Flying Fortresses swatted them away like annoying flies.

While Sakaguchi took Balikpapan, the naval infantry of the Sasebo Special Naval Landing Force would capture Kendari, giving the Japanese an airfield within easy range of Timor and other important targets. The Dutch defenders here numbered about 400, almost all of them local militia. Just before the invasion came their machine guns were re-allocated to Makassar on the opposite coast of the island, but they did receive 30 trucks to motorize them. Unfortunately, the drivers did not remain, and none of the Celebesan soldiers knew how to drive them.

When they Japanese arrived on 24 January, the American seaplane tender Childs, which had been offloading aviation gas, slipped away and eluded four Japanese destroyers who lookouts apparently mistook the green-painted former destroyer for a merchant ship. The Japanese SNLF troops caught the Dutch by surprise and only suffered two wounded; here the Dutch did only minor damage to the airfield and the Japanese command reported that it was immediately available for use. The only real damage to the Japanese side came from a collision between the cruiser Nagara and destroyer Hatsuharu. The Japanese murdered the handful of prisoners they took, but most of the Dutch troops fled into the jungle where the local recruits almost all deserted.

Despite the losses to transports and the men and materiel aboard them, the Japanese had secured Borneo. The next target would be the heart of the Dutch East Indies, the teeming island of Java.

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Mike Bennighof is president of Avalanche Press and holds a doctorate in history from Emory University. A Fulbright Scholar and NASA Journalist in Space finalist, he has published a great many books, games and articles on historical subjects; people are saying that some of them are actually good. He lives in Birmingham, Alabama with his wife, three children, and new puppy. He misses his lizard-hunting Iron Dog, Leopold.

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