Invasion of Sumatra (1942)
Encyclopedia
The Invasion of Sumatra by Imperial Japanese forces took place from 14 February to 28 March 1942. The invasion was part of the Pacific War
in South-East Asia during World War II
and led to the capture of the island. The invasion of Sumatra was planned to occur prior to the invasion of Java to destroy the west flank of the allies and to give access to Java.
, the allies began troop transfers in December 1941 to Sumatra
. First British and Australian bombers were moved in relays to the south of the island to recuperate from losses on the Malay peninsula. In addition, a convoy brought about 3,400 Australian soldiers to Sumatra.
In a joint conference on 16 December, the Dutch requested aid to strengthen the defence of Sumatra and Java. Furthermore, plans were made in Sabang to establish Medan and Pekanbaru supply camps. However, these plans were revised on the 27 December, with airfields P1 (Pangkalanbenteng) and P2 (Praboemoelih) near Palembang selected as locations of the new headquarters to station an operational bomber relay. P2 had not been discovered by the Japanese reconnaissance flights up to then. Because of the poor state of the airfields, the relocation began on 31 December; available ground staff arrived at the beginning of January. Another airfield was located in Oosthaven, today's Bandar Lampung. Works on roads were also started in Medan and Pekanbaru. Lack of anti-aircraft guns was remedied with the delivery of six heavy and six light Bofors anti-aircraft guns to each Palembang airfield. Another eight anti-aircraft guns were placed at the refineries. However, there was an ammunition shortage, because the ammunition delivery ships had been sunk by the Japanese during the crossing.
and four Hurricanes
. Two other Hurricanes were damaged. On the ground, the Japanese destroyed two Buffalos. During the attack, the Allies shot down only a single Japanese Nakajima Ki-43
. As a countermove, the Allies began night raids against the Japanese lines on the Malay peninsula and provided air protection for refugee convoys from Singapore.
For Operation "L", the Japanese army had transported the 229th Infantry Regiment of the 38th Infantry Division from Hong Kong
to Cam Ranh Bay
in Indo-China. From there, eight transports departed on 9 February 1942, protected by a cruiser, four destroyers, five minesweepers and two submarine hunters under the command of Rear Admiral Shintarō Hashimoto
to invade Bangka and Palembang. The next day Rear Admiral Jisaburō Ozawa
followed with the Western Covering Fleet, consisting of the flagship cruiser Chô with five other cruisers and three destroyers and an Air Group under the command of Rear Admiral Kakaji Kakuta
consisting of the aircraft carrier Ryūjō
and one destroyer. The bulk of the invasion force followed on 11 February in thirteen transports which were accompanied by a heavy cruiser, a frigate, four destroyers and a submarine hunter.
The Dutch tanker Manvantara was sunk by Japanese aircraft on 13 February 1942 in the Java Sea. Four Dutch submarines laid in wait at the Anambas Islands, however, these could not reach the Japanese fleet. The transports reached Singapore, and subsequently Allied refugee freighters which were on the move in the direction of Java and Sumatra were attacked by Japanese airplanes from the Ryūjō. Apart from that they also damaged the British light cruiser HMS Durban
which had to turn away to Colombo. The Japanese attacked repeatedly with airplanes from the Ryūjō and with land-based bombers from the Genzan aerial unit. Two Allied tankers, a steamboat and many smaller vessels were sunk, another tanker and two transports severely damaged.
At 8 o'clock in the morning on 14 February the air-raid wardens warned Palembang of a big Japanese attack wave which was in flight to the town. All available Allied air forces were at that time on missions to protect the sea convoys and were not in radio reach. Firstly, a wave of Japanese bombers dropped its load on airfield P1, followed by strafing from accompanying fighters. Shortly afterwards, 260 Japanese paratroopers of the First Japanese Airborne Division landed at P1. They came from the captured airfield of Kahang in Malaya. The second wave consisting of 100 paratroopers from Kluang landed shortly afterwards some kilometres to the west of P1 near the refinery.
In defence were only 150 British anti-aircraft men, 110 Dutch soldiers and 75 British ground defence men were at P1. While the Japanese piled up vehicles to make road blocks small gun battles broke out with the defenders and some landed airplanes succeeded in refuelling. The airplanes immediately flew to the undiscovered airfield, P2. The headquarters should also move to P2 after news from the refinery and from Palembang arrived. In the afternoon it came to a deadlock. The British still held the airfield, but, their ammunition was short and they were hindered by the street blockade. After a false report of other Japanese parachute landings at about 25 kilometres of distance spread the British commander, H. G. Maguire, decided to evacuate the airfield and the town. On the next day another 100 Japanese landed at the refinery. After a violent fight which continued the whole day, the defenders forced back the Japanese, but the refinery was heavily damaged by machine gun fire and was aflame. Other surrounding smaller facilities had been damaged.
Meanwhile, the escort fleet had sortied under vice admiral Ozawa to the north of Bangka to form a far-reaching cover screen for the Japanese landings which took place shortly afterward. A vanguard went ashore on Bangka, while the main units had landed near Palembang at the mouth of the Musi river and advanced on the along the river to the town. A defence at the mouth had not been put up by the Dutch because it was judged by them as useless against the artillery fire expected from the ships.
At this time Japanese reconnaissance planes sighted the ABDA fleet, under Rear Admiral Karel Doorman
, at Gasperstrasse on a northerly course. On Wavell's order, Doorman had collected the fleet, consisting of the Dutch cruisers De Ruyter
, Java
and Tromp
as well as the British cruiser HMS Exeter
and the Australian light cruiser HMAS Hobart with ten destroyers, to the south of Bali and sortied on 14 February in the direction of Sumatra. Japanese fighter aircraft of the Ryūjō and from Malaya attacked the ABDA fleet at midday of the next day and made Doorman pull back all his ships to the south.
The invasion fleet at Bangka straight had also been spotted by British reconnaissance planes from P2. In the early morning 22 Hurricanes, 35 Blenheims and 3 Hudsons, tried to attack the ships. Nevertheless, they were engaged by Japanese airplanes in violent aerial battles. At P2 the news of the Japanese parachute landing at P1 became known. The commander initiated the preparations for an evacuation of the airfield. Then, however, the later arriving news that P1 had not been given up yet, led to the returned machines being prepared at night for a new attack. In the morning fog the allied fighter aircraft made violent attacks against the Japanese who had just begun their landing at the mouth of the Musi. Japanese airplanes withdrew shortly after the battle began, so that the allies succeeded in getting direct hits on the transporters. Twenty landing crafts were sunk and, besides, hundreds of Japanese were killed. The last allied results achieved were by Hurricanes attacking unprotected landing craft on the southwest beach of Bangka.
Meanwhile the Dutch command had sent the order for the destruction of the oil dumps and rubber dumps. The ferries on the Musi should be destroyed within the next hour so they could not be used by the Japanese. Also the defenders of P1 were to start a quick retreat. On the night of the 15th of February Japanese units, which had survived the air raid at the Musi mouth, reached Palembang and relieved the paratroopers landed at P1 and the refinery.
Field Marshal Archibald Percival Wavell was the Supreme Commander of ABDA. In the morning of the 15th of February Wavell arranged a regular retreat to the embarkation of his troops at Oosthaven where several small ships lay in the harbour. There 2,500 British RAF members, 1,890 British infantrymen, 700 Dutch soldiers and about 1,000 civilians were evacuated by means of twelve ships on the 17th of February. The Australian corvette Burnie covered the retreat and destroyed harbour facilities and oil tanks. A smaller steamboat lay at anchor a little while longer in the harbour to be able to take up later arriving refugees.
In the interim the Japanese had completely taken Palembang and had destroyed the oil refineries at two smaller stations. Small troop transporters steamed up the river to Menggala.
All remaining airworthy allied fighter aircraft were flown out on the 16th of February. The staff of the airfields proceeded by sea to India. Because the Japanese did not advance for the time being to Oosthaven, a task force went ashore there once again on the 20th of February to save airplane spare parts as well as to destroy the other usable facilities.
On the 24 February the Japanese reached Gelumbang.
March 3-7 saw vicious firefights as Japanese units tried to cross the river. As the offensive ground to a halt, Dutch spies returned with reports of many dead and wounded. They also reported that the regiment now numbered only about 200 men. Buoyed by the reports, Major Hazenberg decided to counterattack on the night of March 8-9. On the 7-8th, several native boats were assembled out of sight and loaded with supplies and ammunition while assault groups formed. However, on the 8th of March the news of the capitulation of Java arrived, all offensive efforts had to be broken off because Sumatra was dependent on supply deliveries from Java and it was decided to take a defensive course. West Sumatra had to be left to the Japanese and only a small part of the north would be held with the available forces as long as possible, until a sea evacuation could be organised.
In the retreat the KNIL units destroyed all airfields and harbour facilities. They withdrew into defensive positions at the south entrance of the Alice valley where they planned to detain the Japanese as long as possible. Should the positions fall, a guerrilla war from the environs was planned. Indeed it would turn out to be difficult because the population of Sumatra did not cooperate with the Dutch, as a long-standing colonial power, but on the contrary would betray to the Japanese the Dutch positions. This was especially clear when the Dutch wanted to move about 3,000 Europeans and Christian civilians in refugee camps from the coast of Aceh province. A Muslim uprising which broke out shortly after the beginning of the Japanese landings prevented the action.
Operation T began on 28 February when 27 transports with 22,000 soldiers of the Imperial Guard aboard sailed from Singapore. They were split in four convoys and were accompanied by three cruisers, ten destroyers, patrol boats and submarine-defensive units. Because the allied air defence and sea defence was non-existent at that time, they reached north Sumatra absolutely unchecked.
On 12 March the Kobayashi Detachment took Sabang Island and the airfield at Koetaradja without running into opposition. Yoshida Detachment had landed south of Idi with a single infantry battalion with orders to seize the Lantja and Pangkalang Brandan oilfields. It would then drive south towards Medan and apply pressure on Dutch positions there. The main force landed about four miles northwest of Tandjoengtiram. It was to drive along the Pematang Siantar-Balige-Taroetoeng Highway and cut off any KNIL forces attempting to withdrawal from Medan and also to drive north to Medan and seize the airfield there..
Sumatra fell on 28 March when the Dutch Major General R. T. Overakker with 2,000 soldiers surrendered near the town of Kutatjane in North Sumatra. Many allied prisoners were forced by the Japanese to construct a railroad line between Pekanbaru and Moera. (Overakker together with other officers of the KNIL in captivity were shot in 1945 in view of the impending defeat of the Japanese.)
Pacific War
The Pacific War, also sometimes called the Asia-Pacific War refers broadly to the parts of World War II that took place in the Pacific Ocean, its islands, and in East Asia, then called the Far East...
in South-East Asia during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
and led to the capture of the island. The invasion of Sumatra was planned to occur prior to the invasion of Java to destroy the west flank of the allies and to give access to Java.
Background
After the Japanese successfully conquered the Malay PeninsulaMalay Peninsula
The Malay Peninsula or Thai-Malay Peninsula is a peninsula in Southeast Asia. The land mass runs approximately north-south and, at its terminus, is the southern-most point of the Asian mainland...
, the allies began troop transfers in December 1941 to Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
. First British and Australian bombers were moved in relays to the south of the island to recuperate from losses on the Malay peninsula. In addition, a convoy brought about 3,400 Australian soldiers to Sumatra.
In a joint conference on 16 December, the Dutch requested aid to strengthen the defence of Sumatra and Java. Furthermore, plans were made in Sabang to establish Medan and Pekanbaru supply camps. However, these plans were revised on the 27 December, with airfields P1 (Pangkalanbenteng) and P2 (Praboemoelih) near Palembang selected as locations of the new headquarters to station an operational bomber relay. P2 had not been discovered by the Japanese reconnaissance flights up to then. Because of the poor state of the airfields, the relocation began on 31 December; available ground staff arrived at the beginning of January. Another airfield was located in Oosthaven, today's Bandar Lampung. Works on roads were also started in Medan and Pekanbaru. Lack of anti-aircraft guns was remedied with the delivery of six heavy and six light Bofors anti-aircraft guns to each Palembang airfield. Another eight anti-aircraft guns were placed at the refineries. However, there was an ammunition shortage, because the ammunition delivery ships had been sunk by the Japanese during the crossing.
Operation L
The first Japanese air raid came on 6 February and hit the P1 airfield at Palembang. The Allies lost two Blenheim bombersBristol Blenheim
The Bristol Blenheim was a British light bomber aircraft designed and built by the Bristol Aeroplane Company that was used extensively in the early days of the Second World War. It was adapted as an interim long-range and night fighter, pending the availability of the Beaufighter...
and four Hurricanes
Hawker Hurricane
The Hawker Hurricane is a British single-seat fighter aircraft that was designed and predominantly built by Hawker Aircraft Ltd for the Royal Air Force...
. Two other Hurricanes were damaged. On the ground, the Japanese destroyed two Buffalos. During the attack, the Allies shot down only a single Japanese Nakajima Ki-43
Nakajima Ki-43
The Nakajima Ki-43 Hayabusa was a single-engine land-based tactical fighter used by the Imperial Japanese Army Air Force in World War II...
. As a countermove, the Allies began night raids against the Japanese lines on the Malay peninsula and provided air protection for refugee convoys from Singapore.
For Operation "L", the Japanese army had transported the 229th Infantry Regiment of the 38th Infantry Division from Hong Kong
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
to Cam Ranh Bay
Cam Ranh Bay
Cam Ranh Bay is a deep-water bay in Vietnam in the province of Khánh Hòa. It is located at an inlet of the South China Sea situated on the southeastern coast of Vietnam, between Phan Rang and Nha Trang, approximately 290 kilometers / 180 miles northeast of Hồ Chí Minh City / Saigon.Cam Ranh is...
in Indo-China. From there, eight transports departed on 9 February 1942, protected by a cruiser, four destroyers, five minesweepers and two submarine hunters under the command of Rear Admiral Shintarō Hashimoto
Shintaro Hashimoto
-Web:- Firsthand account of the battle by a member of HMS Vigilant's crew.- Fairly detailed account of the battle...
to invade Bangka and Palembang. The next day Rear Admiral Jisaburō Ozawa
Jisaburo Ozawa
was an admiral in the Imperial Japanese Navy during World War II. He was the last Commander-in-Chief of Combined Fleet. Many military historians regard Ozawa as one of the most capable Japanese flag officers.-Biography:...
followed with the Western Covering Fleet, consisting of the flagship cruiser Chô with five other cruisers and three destroyers and an Air Group under the command of Rear Admiral Kakaji Kakuta
Kakuji Kakuta
, was an admiral in the Imperial Japanese Navy during World War II. He is noted for his role in commanding Japanese naval aviation units in the Pacific War.-Biography:...
consisting of the aircraft carrier Ryūjō
Japanese aircraft carrier Ryujo
Ryūjō was a light aircraft carrier of the Imperial Japanese Navy. She was laid down by Mitsubishi at Yokohama in 1929, launched in 1931 and commissioned on 9 May 1933. Her final design resulted in a top-heavy unstable vessel and within a year she was back at Kure Naval Yard for modification...
and one destroyer. The bulk of the invasion force followed on 11 February in thirteen transports which were accompanied by a heavy cruiser, a frigate, four destroyers and a submarine hunter.
The Dutch tanker Manvantara was sunk by Japanese aircraft on 13 February 1942 in the Java Sea. Four Dutch submarines laid in wait at the Anambas Islands, however, these could not reach the Japanese fleet. The transports reached Singapore, and subsequently Allied refugee freighters which were on the move in the direction of Java and Sumatra were attacked by Japanese airplanes from the Ryūjō. Apart from that they also damaged the British light cruiser HMS Durban
HMS Durban (D99)
HMS Durban was a Danae-class light cruiser of the Royal Navy. She was launched from the yards of Scotts Shipbuilding and Engineering Company on 29 May 1919 and commissioned on 1 November 1921.-Early career:...
which had to turn away to Colombo. The Japanese attacked repeatedly with airplanes from the Ryūjō and with land-based bombers from the Genzan aerial unit. Two Allied tankers, a steamboat and many smaller vessels were sunk, another tanker and two transports severely damaged.
At 8 o'clock in the morning on 14 February the air-raid wardens warned Palembang of a big Japanese attack wave which was in flight to the town. All available Allied air forces were at that time on missions to protect the sea convoys and were not in radio reach. Firstly, a wave of Japanese bombers dropped its load on airfield P1, followed by strafing from accompanying fighters. Shortly afterwards, 260 Japanese paratroopers of the First Japanese Airborne Division landed at P1. They came from the captured airfield of Kahang in Malaya. The second wave consisting of 100 paratroopers from Kluang landed shortly afterwards some kilometres to the west of P1 near the refinery.
In defence were only 150 British anti-aircraft men, 110 Dutch soldiers and 75 British ground defence men were at P1. While the Japanese piled up vehicles to make road blocks small gun battles broke out with the defenders and some landed airplanes succeeded in refuelling. The airplanes immediately flew to the undiscovered airfield, P2. The headquarters should also move to P2 after news from the refinery and from Palembang arrived. In the afternoon it came to a deadlock. The British still held the airfield, but, their ammunition was short and they were hindered by the street blockade. After a false report of other Japanese parachute landings at about 25 kilometres of distance spread the British commander, H. G. Maguire, decided to evacuate the airfield and the town. On the next day another 100 Japanese landed at the refinery. After a violent fight which continued the whole day, the defenders forced back the Japanese, but the refinery was heavily damaged by machine gun fire and was aflame. Other surrounding smaller facilities had been damaged.
Meanwhile, the escort fleet had sortied under vice admiral Ozawa to the north of Bangka to form a far-reaching cover screen for the Japanese landings which took place shortly afterward. A vanguard went ashore on Bangka, while the main units had landed near Palembang at the mouth of the Musi river and advanced on the along the river to the town. A defence at the mouth had not been put up by the Dutch because it was judged by them as useless against the artillery fire expected from the ships.
At this time Japanese reconnaissance planes sighted the ABDA fleet, under Rear Admiral Karel Doorman
Karel Doorman
Karel Willem Frederik Marie Doorman was a Dutch Rear Admiral who commanded ABDACOM Naval forces, a hastily-organized multinational naval force formed to defend the East Indies against an overwhelming Imperial Japanese attack. Doorman was killed and the main body of ABDACOM Naval forces destroyed...
, at Gasperstrasse on a northerly course. On Wavell's order, Doorman had collected the fleet, consisting of the Dutch cruisers De Ruyter
HNLMS De Ruyter (1935)
HNLMS De Ruyter was a light cruiser of the Royal Netherlands Navy, the lead ship of her class. She was originally designed as a ship with a lighter armament due to financial problems and the pacifist movement. Later in the design stage, an extra gun turret was added and the armor was improved...
, Java
Java class cruiser
The Java class was a class of light cruisers of the Royal Netherlands Navy, named after the island of Java in the Dutch East Indies . Originally, three ships were planned: HNLMS Java, HNLMS Sumatra, and HNLMS Celebes...
and Tromp
HNLMS Tromp (1937)
HNLMS Tromp was the lead ship of the Tromp-class light cruisers of the Royal Netherlands Navy during and after World War II.Originally designated as a flotilla leader and a torpedo cruiser in the Deckers Fleet Plan of 1931, she was laid down at the "Nederlandsche Scheepsbouw Maatschappij" ,...
as well as the British cruiser HMS Exeter
HMS Exeter (68)
HMS Exeter was a York class heavy cruiser of the Royal Navy that served in World War II. She was laid down on 1 August 1928 at the Devonport Dockyard, Plymouth, Devon. She was launched on 18 July 1929 and completed on 27 July 1931...
and the Australian light cruiser HMAS Hobart with ten destroyers, to the south of Bali and sortied on 14 February in the direction of Sumatra. Japanese fighter aircraft of the Ryūjō and from Malaya attacked the ABDA fleet at midday of the next day and made Doorman pull back all his ships to the south.
The invasion fleet at Bangka straight had also been spotted by British reconnaissance planes from P2. In the early morning 22 Hurricanes, 35 Blenheims and 3 Hudsons, tried to attack the ships. Nevertheless, they were engaged by Japanese airplanes in violent aerial battles. At P2 the news of the Japanese parachute landing at P1 became known. The commander initiated the preparations for an evacuation of the airfield. Then, however, the later arriving news that P1 had not been given up yet, led to the returned machines being prepared at night for a new attack. In the morning fog the allied fighter aircraft made violent attacks against the Japanese who had just begun their landing at the mouth of the Musi. Japanese airplanes withdrew shortly after the battle began, so that the allies succeeded in getting direct hits on the transporters. Twenty landing crafts were sunk and, besides, hundreds of Japanese were killed. The last allied results achieved were by Hurricanes attacking unprotected landing craft on the southwest beach of Bangka.
Meanwhile the Dutch command had sent the order for the destruction of the oil dumps and rubber dumps. The ferries on the Musi should be destroyed within the next hour so they could not be used by the Japanese. Also the defenders of P1 were to start a quick retreat. On the night of the 15th of February Japanese units, which had survived the air raid at the Musi mouth, reached Palembang and relieved the paratroopers landed at P1 and the refinery.
Field Marshal Archibald Percival Wavell was the Supreme Commander of ABDA. In the morning of the 15th of February Wavell arranged a regular retreat to the embarkation of his troops at Oosthaven where several small ships lay in the harbour. There 2,500 British RAF members, 1,890 British infantrymen, 700 Dutch soldiers and about 1,000 civilians were evacuated by means of twelve ships on the 17th of February. The Australian corvette Burnie covered the retreat and destroyed harbour facilities and oil tanks. A smaller steamboat lay at anchor a little while longer in the harbour to be able to take up later arriving refugees.
In the interim the Japanese had completely taken Palembang and had destroyed the oil refineries at two smaller stations. Small troop transporters steamed up the river to Menggala.
All remaining airworthy allied fighter aircraft were flown out on the 16th of February. The staff of the airfields proceeded by sea to India. Because the Japanese did not advance for the time being to Oosthaven, a task force went ashore there once again on the 20th of February to save airplane spare parts as well as to destroy the other usable facilities.
On the 24 February the Japanese reached Gelumbang.
Operation T
The allied units remaining on Sumatra, primarily KNIL members, withdrew into the middle and northern provinces of the island. The Dutch planned a reconquest of Palembang from there and the expulsion of the Japanese from the island. Unfortunately, the offensive-minded Japanese weren’t about to let the KNIL carry out its plans and aggressively pursued from Palembang with a highly motorized reconnaissance regiment numbering approximately 750 men. The outnumbered and retreating forces under Major C.F. Hazenberg numbered only about 350 KNIL regulars in two companies. They were also badly dispersed and could only fight delaying actions, which allowed the better trained and equipped Japanese to rapidly advance. After three weeks, the Japanese were finally contained at Moearatebo on March 2nd. Dutch reinforcements from Padangpandjang were able to move up when heavy rains made the rivers all but impassible by running 27 feet over their flood gauges. This delay gave local KNIL commanders time to deploy additional units from the middle provinces, thus preventing the retreating units’ flank from being turned.March 3-7 saw vicious firefights as Japanese units tried to cross the river. As the offensive ground to a halt, Dutch spies returned with reports of many dead and wounded. They also reported that the regiment now numbered only about 200 men. Buoyed by the reports, Major Hazenberg decided to counterattack on the night of March 8-9. On the 7-8th, several native boats were assembled out of sight and loaded with supplies and ammunition while assault groups formed. However, on the 8th of March the news of the capitulation of Java arrived, all offensive efforts had to be broken off because Sumatra was dependent on supply deliveries from Java and it was decided to take a defensive course. West Sumatra had to be left to the Japanese and only a small part of the north would be held with the available forces as long as possible, until a sea evacuation could be organised.
In the retreat the KNIL units destroyed all airfields and harbour facilities. They withdrew into defensive positions at the south entrance of the Alice valley where they planned to detain the Japanese as long as possible. Should the positions fall, a guerrilla war from the environs was planned. Indeed it would turn out to be difficult because the population of Sumatra did not cooperate with the Dutch, as a long-standing colonial power, but on the contrary would betray to the Japanese the Dutch positions. This was especially clear when the Dutch wanted to move about 3,000 Europeans and Christian civilians in refugee camps from the coast of Aceh province. A Muslim uprising which broke out shortly after the beginning of the Japanese landings prevented the action.
Operation T began on 28 February when 27 transports with 22,000 soldiers of the Imperial Guard aboard sailed from Singapore. They were split in four convoys and were accompanied by three cruisers, ten destroyers, patrol boats and submarine-defensive units. Because the allied air defence and sea defence was non-existent at that time, they reached north Sumatra absolutely unchecked.
On 12 March the Kobayashi Detachment took Sabang Island and the airfield at Koetaradja without running into opposition. Yoshida Detachment had landed south of Idi with a single infantry battalion with orders to seize the Lantja and Pangkalang Brandan oilfields. It would then drive south towards Medan and apply pressure on Dutch positions there. The main force landed about four miles northwest of Tandjoengtiram. It was to drive along the Pematang Siantar-Balige-Taroetoeng Highway and cut off any KNIL forces attempting to withdrawal from Medan and also to drive north to Medan and seize the airfield there..
Sumatra fell on 28 March when the Dutch Major General R. T. Overakker with 2,000 soldiers surrendered near the town of Kutatjane in North Sumatra. Many allied prisoners were forced by the Japanese to construct a railroad line between Pekanbaru and Moera. (Overakker together with other officers of the KNIL in captivity were shot in 1945 in view of the impending defeat of the Japanese.)