Key point: Many factors influenced Tokyo's decision and preparations were made well in advance.
By the time the attack on Pearl Harbor plunged the United States into World War II, Japan had been preparing for an all-out offensive in the Pacific for months.
Japan relied on imports of raw materials and natural resources to survive. Rubber, tin, iron, and especially oil had to be imported for Japanese industry to function. The same raw materials were also essential for the Japanese war machine.
In 1894-1895, Japan defeated China in a short war and gained control of the island
of Formosa, part of Korea, and a bit of Manchuria. Along with these territories came all their natural resources. In 1905, after Japan defeated Russia in the Russo-Japanese War, the Empire of the Sun took control of all of Korea and part of Manchuria that had earlier been gobbled up by the Russians.
On September 19, 1931, in the midst of a worldwide depression, Japan staged an incident at a railway station on the Korean border of Manchuria, which it used as an excuse to invade the mineral-rich Chinese province. When the League of Nations condemned the act, Japan resigned from the League. In 1936, to expand her navy, Japan renounced the 1922 Washington Naval Treaty, which had limited the size of the Japanese Navy. In July 1937, Japan launched a full-scale invasion of China on the pretext that Chinese soldiers had fired on Japanese troops in Manchuria. Although Japan could not conquer all of China, by 1939 it had captured almost all of the important port cities and had firm control of the raw material that went into or out of the Asian giant.
In June 1940, after Japan moved into French Indochina while France was under Nazi occupation, the U.S. Congress passed the Export Control Act, which prohibited the export of “strategic minerals and chemicals, aircraft engines, parts, and equipment” to Japan. Conspicuously absent from this list was crude oil.
The already strained relations between the United States and Japan worsened in September 1940 when the Japanese signed the Tripartite Pact with Nazi Germany and Fascist Italy. Hitler, who was already planning to start a war in Europe, was hoping that the Tripartite Pact would encourage Japan to invade the British holdings in the Far East to pin down forces already there.
At the same time, the Japanese hoped that the pact would provide security as they formulated plans to invade and capture the rich oilfields of the Netherlands East Indies. In response to the Tripartite Pact, the United States embargoed even more material—brass, copper, and iron. Still, President Franklin D. Roosevelt stopped short of barring Japanese purchases of oil.
By the spring of 1941, Japan signed a five-year nonaggression pact with Russia, assuring that her backdoor was closed and safe. Next, Japan moved more troops into French Indochina and began eyeing the Netherlands East Indies. In response to the troop movements, Roosevelt froze all Japanese assets in the United States and after much consideration finally placed an embargo on crude oil.
On the heels of the American embargo, the Dutch proclaimed that the Netherlands East Indies would also stop selling oil to Japan. To conquer the Netherlands East Indies and capture its vital oilfields, Japan first had to eliminate the British stronghold of Singapore, crush the American forces in the Philippines, and cripple the U.S. Pacific Fleet at Pearl Harbor. Within 24 hours on December 7, 1941, Japan launched attacks against Pearl Harbor, the Philippines, Singapore, Hong Kong, Northern Malaya, Thailand, Guam, Wake Island, and Midway Atoll and began planning to capture the island of Sumatra, east of Java, along with the oil refineries and a key airfield in the vicinity.
In December 1940, the Japanese Army began experimenting with airborne forces. Training of the first volunteers took place at Ichigaya near Tokyo. Requirements for the unit were rigid. Most of the volunteers were between the ages of 20 and 25, and officers could be no older than 28. All had to go through a rigid medical examination. Additional psychological and physical tests were administered and, acting on the belief that paratroopers had to have cat-like abilities to land safely, volunteers were given intense physical fitness training similar to that of a gymnast.
After about 250 volunteers were selected, training moved to a Tokyo amusement park that had a special ride featuring a 165-foot parachute drop. Historians Gordan Rottman and Akira Takizawa wrote, “Thrill seekers were attached to a canopy that was hoisted by cable before being released to float to the ground. Because the existence of the paratroop unit was secret, trainees were directed to visit the park disguised as university students, to experience a couple of simulated descents.” Additional training consisted of somersaults and tumbling, leaping from various heights to learn landing techniques and, finally, actual jumps from moving planes.
Once the original group of volunteers was sufficiently trained, it was broken into cadres to absorb new trainees. By January 1942, the Army had enough paratroopers trained to form the 1st Raiding Brigade under Colonel Seiichi Kume consisting of the 1st Raiding Brigade Headquarters, the 1st Raiding Regiment (Major Takeo Takeda), and the 2nd Raiding Regiment (Major Takeo Komura). Additionally, the 1st Raiding Flying Regiment (Major Akihito Niihara), an air transport group, was attached to the brigade so that the paratroopers would have their own autonomous airplane group. Each regiment consisted of only about 700 men, rather than the 3,800 of a standard infantry regiment. Each regiment included a regimental headquarters group, three rifle companies, and an engineer company.
Preparations for the Army parachute drop on Sumatra had actually been completed by late December 1941, but an accidental fire aboard the cargo ship Meiko Maru on January 3, 1942, which was transporting the 1st Raiding Regiment to an airfield on the Malay Peninsula, caused the paratroopers to abandon ship without their parachutes, equipment, and weapons. Exhausted and battered from their harrowing ordeal and stranded on Hainan Island off the northern coast of French Indochina, the paratroopers were in no shape to stage a combat parachute drop.
When word of the disaster reached the Imperial Army General Staff, they turned to Major Komura and his 2nd Raiding Regiment. Although the unit was still being organized, approximately 450 paratroopers drew weapons, equipment, and parachutes. On January 15, the understrength 2nd Raiding Regiment left Kyushu, arriving at Phnom Penh, Cambodia, on February 2.
The 2nd Raiding Regiment was broken into the 1st and 2nd Attack Groups for the air assaults on the Palembang airfield and oil refineries. The 1st Attack Group, consisting of about 350 officers and men, would be transported to the area in the 1st Raiding Flying Regiment’s Tachikawa Type LO “Thelma” and Mitsubishi Ki-57 Type 100 Model 1 “Topsy” aircraft, with a scheduled drop on February 14. One day later, the 2nd Attack Group, containing only 90 officers and men, would be dropped by the 12th Transport Chutai. Inexplicably, the small cargo containers carrying the rifles, machine guns, ammunition, and other supplies would be dropped by the 98th Sentai from 27 twin-engine Mitsubishi Type 97 “Sally” medium bombers. This plan worried the paratroopers. “If the [containers] were misdropped or delayed,” wrote historians Rottman and Takizawa, “the paratroopers on the ground would be forced to fight a well-armed enemy with only pistols and grenades.”
Both flights were to be escorted by Nakajima Ki-43 “Oscar” fighter planes from the 59th and 64th Sentai. Additionally, the initial drop would be preceded by nine Kawasaki Ki-48 Type 99 “Lily” light bombers from the 90th Sentai dropping antipersonnel bombs across the Dutch airfield.
By February 13, the entire attack force had moved from Cambodia to the west side of the Malay Peninsula, with the 1st Attack Group assembling at the recently captured Allied airfields at Keluang and Kahang and the 2nd Attack Group moving to Sungai Petani. Toasting each other with saké, the officers and men prepared for their early morning drop at Palembang, the capital of Sumatra.
Palembang, with a population of more than 108,000, was situated on the Moesi River about 50 miles inland from the Banka Strait. It was said that its oilfields were the best in Southeast Asia. Two oil refineries had been constructed about four miles east of the town on the south side of the Moesi River. A tributary of the Moesi, the Komering River, divided the two refineries. On the east bank and farthest away from Palembang was the Nederlandsche Koloniale Petroleum Maatschappij (NKPM), a refinery for the Standard Oil Company. On the west bank was the Bataafsce Petroleum Maatschappij (BPM), owned by Shell Oil. The latter refinery was built as two separate installations, one opposite the NKPM refinery on the west side of the Komering River and the other a short distance away on the south bank of the Moesi River.
Even though the Dutch could predict that the Japanese would want the two refineries intact, they did not intend to destroy the facilities prematurely. In addition to a well-known civilian airfield called Pangkalanbenteng (P1), eight miles north of Palembang, there was a recently constructed military airfield, Praboemoelih (P2), 40 miles to the south. P1 had been used by civilian aircraft for years and had a hard concrete runway, barracks buildings, and control tower. Unfortunately for the Dutch, P1 was well known to the Japanese. However, the newly established P2 had a cleverly concealed dirt runway with room beneath the surrounding jungle canopy to hide Allied airplanes. Because of its well-hidden location, P2 was unknown to the Japanese.