In 1942, the Dutch Empire in Asia collapsed in a matter of months, but for millions of Indonesians, Japan’s arrival wasn’t just another occupation—it was a moment of hope. Tokyo promised liberation from centuries of colonial rule. Nationalist leaders like Sukarno and Hatta saw a chance to finally build their own nation by working with the enemy. But behind the slogans of “Asia for Asians” lay a brutal reality: forced labor, hunger, and control.
During the 1930s, the Dutch East Indies—modern-day Indonesia—was one of the richest colonies in Asia, supplying the Netherlands with oil, rubber, and tin. But beneath the surface, resentment was growing. A new generation of nationalists, including Sukarno and Mohammad Hatta, were calling for independence. The Dutch responded with repression: political movements were tightly monitored, and many leaders were arrested or exiled.
By the late 1930s, Dutch rule looked secure, but it was brittle, built on censorship, inequality, and economic dependence. Then came World War II. When Germany invaded the Netherlands in 1940, the colonial administration in Indonesia was cut off from Europe. The Dutch tried to strengthen local defenses and align with the Allies, but their forces were weak and outdated.
Meanwhile, Japan, hungry for resources to fuel its empire, set its sights on the Dutch East Indies oil fields. By early 1942, Japan’s military swept through Southeast Asia with lightning speed. The Dutch East Indies fell within months. For Indonesians, centuries of Dutch rule had ended, but what followed was not freedom—it was a new and far harsher occupation.
The Japanese occupation of Indonesia, from 1942 to 1945, was one of the most transformative and brutal periods in the country’s modern history. When Japan drove out the Dutch, many Indonesians initially greeted them as liberators. After all, Japan claimed to be fighting for “Asia for Asians,” promising to end Western colonialism. But this promise soon faded.
Japan’s main goal was to exploit Indonesia’s vast resources—especially oil, rice, and labor—for its war effort. The occupation was divided into three zones, each ruled by a branch of the Japanese military. Sumatra was occupied by the Japanese 25th Army. Java and Bali were controlled by the 16th Army.
The islands north and east of Java, including Celebes and South Borneo, were under the Japanese Navy. If you ran into a Japanese soldier in the street, you had to make a deep bow. Even cyclists had to dismount or risk a beating. Dutch banks and newspapers were shut down.
Political activities were banned. In the cities, wooden structures with loudspeakers played Japanese music and propaganda all day long. Wherever you went, you heard Kimigayo, the Japanese national anthem. News broadcasts were in Indonesian, Javanese, and Sundanese, but never in Dutch.
There were daily Japanese lessons and gymnastics. Owners of radios had to have them locked so they could be used only for official Japanese broadcasts. Listening to foreign stations in secret could be punished by death—and often was. Daily life quickly became harsh.
Food and goods were heavily rationed, inflation soared, and millions were forced into hard labor as romusha workers, sent to build roads, railroads, and military facilities. Many never returned home. The Japanese administrators believed the peoples of Sumatra and Java were more politically aware than other Southeast Asians and hoped that some would be actively willing to defend their Greater East Asia Co-Prosperity Sphere. The occupation changed Indonesian society in profound ways.
The Japanese needed local cooperation, so they turned to nationalist leaders like Sukarno and Mohammad Hatta. They were allowed to organize mass movements, speak to crowds, and spread nationalist ideas—though always under Japanese supervision. The Supreme Command of the Japanese military realized that in the event of an Allied landing, capturing Java would be like “taking sweets from a baby. ” After the invasion, Japanese force levels had been reduced from 55,000 to 11,000 to 13,000 at most, and many of those troops had relatively little training.
That made it essential to mobilize the young generation of Indonesians, not just politically, but also as a military force. Japan would train Indonesians, giving them military discipline and weapon skills. And this experience would play a role in the fight of the Indonesians against the Dutch in the years after the Second World War. So, what units did the Japanese create?
In April 1943, the Japanese raised a force of young volunteers known as the Bedoman Seinendan, which means “youth column. ” The age limits were 14 to 25, later reduced to 22. Mostly raised in urban areas, these youngsters were trained with dummy rifles, as the Japanese were careful not to arm them with real rifles, despite having a considerable amount of booty captured from the Royal Netherlands East Indies Army, the KNIL. By war’s end, the formation counted 460,000 men, including units formed in factories and farms.
The Kaibodan Vigilance Corps was a mass organization for older men aged 25 to 35, raised around the same time as the youth column. These men had to perform local security patrols and air raid precautions. They were given basic military training and bamboo spears to act as home guard in case of any Allied landings. Over 1 million Indonesian men were part of this group, mostly armed with bamboo spears and drills performed with dummy rifles.
The Heiho served as auxiliaries, raised from mid-1943, and can be compared with the Soviet Hilfswillige volunteer auxiliaries who served with the Wehrmacht on the Eastern Front. This attracted some 25,000 former indigenous KNIL personnel, as large numbers of Ambonese POWs were released. They had to take an oath of loyalty to Japan and were sent wherever needed—New Guinea and the distant South Pacific islands of New Britain and Bougainville. Those serving under the Navy were sent to the Pacific islands, the Philippines, and even Burma.
They served as laborers and mostly wore their old KNIL uniforms, albeit with new insignia and Japanese caps. They were only armed when serving for propaganda purposes, or when guarding strategic posts, and some had to man anti-aircraft guns. Java was the most populous and developed island. The Japanese had only 8,500 troops there, and thus they had to rely on a paramilitary force from the Indonesian population.
This force, known as Tentara Sukarela Pembela Tanah Air, meaning “defenders of the homeland,” or in short, PETA, recruited near the end of 1943 on Java and nearby Bali. On Java, 38,870 men were organized into 69 battalions. These forces were supposed to be fully armed, yet shortages of small arms made this hard to realize, as there were only some 17,000 rifles, 700 heavy machine guns, and 90 mortars recorded. As one former PETA officer recalled, “The gymnastic exercises at school, Seinendan for young people, the Heiho auxiliary troops, the PETA battalions, all forms of collective life were designed to ignite nationalism and patriotism.
These methods spread the fighting spirit to the most remote villages. By 1945, we, the world’s gentlest people, had all become tigers. ”
Yet, these tigers didn’t see any military action against the Allies during the war. But an interesting thing occurred in February 1945 when a mutiny took place.
The PETA revolt in Blitar on Java was the largest armed uprising during the Japanese occupation of Indonesia. Around 400 PETA soldiers rebelled to free 250 prisoners. Witnesses described hearing gunfire through the night, and the rebels seized key sites including the police station, Kempeitai headquarters, and telephone exchange, shouting slogans of “Merdeka,” freedom. What shocked the Japanese was that the revolt came not from civilians or communists, but from PETA troops—Indonesians trained and organized by Japan itself.
It was a direct mutiny by their own soldiers. The causes ran deep: resentment over Japanese racism, the exclusion of Indonesians from senior ranks, the plundering of food, mass starvation, and the brutal treatment of romusha forced laborers. In its aftermath, six rebels were executed, unusually lenient for such defiance. Late 1944, the Japanese also raised a new armed militia among the majority Muslim population of Java known as the Army of God, or Hizbullah.
Muslim imams and religious schools helped create a force of 50,000 men. The chronic shortage of rifles made the militia resort to the ubiquitous bamboo spears. On Sumatra, PETA’s equivalent, Giyugun Volunteer Army, was raised totaling between 7,500 and 9,000 volunteers. Other Indonesian paramilitary organizations the Japanese formed included the Gakukotai Student Corps, the Barisan Pelopor Vanguard Corps, and the Barisan Wanita Women’s Corps.
Although reluctant, the Japanese also recruited ethnic Chinese Indonesians in the Kakyo Kaibota Overseas Chinese Vigilance Corps. The Dutch accused Indonesian nationalist leaders Sukarno and Hatta of collaborating with the Japanese. The former PETA officer said about this the following: “Sukarno and Hatta are often said to have collaborated with the Japanese. A parallel is drawn to collaboration with fascists in Western Europe, but that’s unfair.
Don’t forget that Sukarno and Hatta had been freed from prison by the Japanese. Sukarno believed that if we wanted freedom, we had to form our own army with our own officers. He said it was pointless to generate ideas without generating power. In short, PETA was the embryo of the later national army.
It made a huge difference whether a nation was independent or under colonial rule. In a colony, people might choose to cooperate with the occupiers simply because they opposed colonial domination. ”
The Japanese, in fact, promoted what could be called anti-colonial fascism—a mix of authoritarian control and anti-imperialist rhetoric that had no equivalent in Europe. European dictatorships like those of Mussolini in Italy, Salazar in Portugal, and Pétain in Vichy France all possessed colonies and defended imperialism.
None of them stood against it. In contrast, many Indonesians had their own reasons for aligning with Japan, driven by hopes of ending centuries of colonial rule. When Japan surrendered in August 1945, Indonesia was left in chaos and on the brink of revolution. The Japanese occupation had collapsed almost overnight.
Their armies still controlled the cities, but their empire was gone. Into this power vacuum stepped Indonesian nationalists who had spent years preparing under Japanese supervision. On August 17th, 1945, just two days after Japan’s surrender, Sukarno and Mohammad Hatta proclaimed Indonesia’s independence in Jakarta. Across the islands, youth groups and militias took up arms, seizing weapons, police stations, and government offices.
The situation quickly spiraled into violence. With the Dutch still in prison by Japan and the Allied forces slow to arrive, radical youth groups saw an opportunity to wipe out any trace of colonial rule. This period from late 1945 into 1946 became known as the Bersiap, meaning “get ready” in Indonesian. It was a chaotic, violent phase marked by revenge attacks against Europeans, Indo-Europeans, and perceived collaborators.
Thousands were killed, and social order collapsed in many areas. When British and later Dutch troops eventually returned, they found a country transformed. The old colonial hierarchy was gone, replaced by armed Indonesians demanding independence. And what followed was the Indonesian War of Independence, 1945-1949, a brutal four-year conflict.
Though Japan had left devastation behind, its occupation had also awakened a new sense of unity and capability among Indonesians. The people who once served the Japanese now turned their training and organization toward a new goal: defending their independence against the Dutch.
