General Overview of Forts in Java and Sumatra


From Pre History Era to the Era of Islam

Defending from enemies' attacks is most inherent in all living beings. In the lives of humans, they also endeavor to protect themselves, their families, as well as their groups from the attacks of enemies, be they wild animals or fellow human beings, to secure their lives. 

Ever since the pre history time, humans have always tried to build protections that would keep himself and his group. Those defense buildings are the very origins of forts that we know at present. 

In Indonesia, since the pre history time, forts have been built around settlements to protect a group of people who lived in the settlements. Forts at that time were made of stone or earth mounds. Quite a number of remnants of such forts from this era are found in Lampung, Riau, Riau Islands, West Sumatra and North Sumatra.  

Influenced by the incoming Hindu and Buddha religions from India, there began to appear in the Archipelago, Hindu and then Buddhist kingdoms. Those kingdoms ruled several areas in the Archipelago such as the Kuta Kingdom in East Kalimantan which is reported to be the first Hindu Kingdom in the Archipelago. In Sumatra there was the Indrapura Kingdom in Aceh and Sriwijaya Kingdom in Palembang. While in Java there was the Mataram Kingdom, the Majapahit Kingdom and Tarumanegara Kingdom.

Those Nusantara kingdoms had always tried to extend their realms from time to time. Therefore, they develop a reliable system of defense that would protect their area and at the same time launched attacks against areas that had not been conquered.

Several kingdoms built forts as their defense system. Indrapuri Kingdom in Aceh built three forts as its system of defense. The three forts were Indrapuri, Indrapatra and Indrapurwa, built in strategic locations. 

During the era of Islam, the Muslim Kingdoms in the Archipelago built towns and settlements with a strong Muslim influence. 

The coming of Islam in the Archipelago brought a great influence to the development of urban settlements in Indonesia, especially in coastal cities of Java.. In the ensuing development, cities in Java were influenced by Muslim urban characteristics. According to Hourani (t.t. 21-23) there are five Muslim urban characteristics, although in reality there are many variations according to different areas and time.  

  1. Possessing fort


  2. Possessing a compound of settlements of rulers comprising palaces, government buildings and buildings for the security guard.


  3. Possessing civic centers that consist of mosques and schools and markets. 


  4. Possessing people’s settlements with groupings based on ethnicity, religion and skills, and


  5. Outside the fort are the settlements for communities with specific skills and burial grounds.


In South East Asia, particularly in Indonesia, ancient cities were located along the river banks and coastal areas, having their respective type of defense system. Forts were initially built only around palaces, but there are also palaces that have no forts at all. In cities that have palace forts, the economic activities were conducted outside the fort. Then came the time when the ruler, especially in Java, built a town fort, perhaps imitating what European rulers did and also as a response to Dutch military threats (Reid, 1980:242). Nevertheless, in many places the town forts do not encircle the entire town. Generally, town and palace forts at the time consisted of ”cepuri” (inner wall), “baluwarti” outer wall) and ”jagang” (ditch). From the observations made by Dr. Inajati Adrisijanti, it is revealed that basically, forts whether baluwarti or cepuri, in Muslim Mataram government centers were built to protect only the palace and its immediate surroundings, not the whole town. This is evident in the towns of Plered and Kartasura, where the Great Mosque and market were located outside “baluwarti” or town wall. Except in City of Gede, where the baluwarti enclosed the whole town, just like ancient towns in Europe or Middle East.

a.  Cepuri

It is interesting to note that the capital towns of Mataram that became of focus of studies, all have forts. In City of Gede and Kartasura, each had even two forts. In those towns, the cepuri encircled a site that is thought to be the remains of the palace and the open space or “alun-alun” was located outside the wall. The basic shape of the cepuri in those two towns is rectangular and a-symmetrical. Sometime a cepuri is complemented by a dike and artificial lage. In three government center cities of Muslim Mataram kingdoms, the cepuri enclosed the palace which was the residence of the king. The function of cepuri was not only as the boundary that separates the palace from other areas but it is thought to also function as a defense and security facility. This is because of the fact that in City of Gede, the cepuri was encircled by a deep and wide ditch. If the cepuri was only to function as an area boundary, such a ditch (jagang) would not be necessary. The assumption that the encircling wall was also to function as a defense element, can be found in Babad Tanah Jawi which mentions about the encircling wall of City of Gede as follows

....Kacarriyos Kangjeng Sultan Pajang miyos sinwaka.... Para bupati sami matur: “Putra Dalem Senapati-ing-Alaga saestu mirong badhe mengsah...sampun damel beteng sarta lelaren wiyar” (Olthof, 1941:60)

meaning “It is happened that when Sultan Pajang was seated on this throne, the regents came to pay their respects and said Your Highness Son, Senapati-Ing-Alaga is truly going to rebel because (he) had already built a fort and a wide ditch around it

b.  Baluwarti

If a cepuri is considered an inner fort that had multi-functions, as an infrastructure of defense and security for the palace, and as an area boundary, the same assumption is also given to baluwarti (Behrend, 1982: 12-12) In the three ancient towns, remnants have been found which are thought to be the remains of a baluwarti encircling a much bigger area. Compared to the area enclosed by a cepuri. A baluwarti is not always straight but can also be undulating at certain places, following the flow of a river.


A view of Kraton in Solo, showing thw inner wall (cepuri) and outer wall (baluwarti)

c. Jagang

Jagang is a ditch that encircles a cepuri or baluwarti. It canbe a man-made ditch or a natural river like in City of Gede and in Surosowan Palace, Banten where the cepuri was encircled by Cibanten River and canals were made. Forts and jagang are closely related such as at City of Gede where the closely follows the cepuri. The same happens with the baluwarti and its jagang, although the West and part the East sides were portions of a natural river. However, it can be said that jagang is not a compulsory element of a fort.

In his book on Aceh Kingdom, Denys Lombard made the analysis based on several travel notes. 1. Notes from Davis when he visited Aceh in 1599: “There standeth a Fort made of stone, round, without covering battlements or flankers, low walled, like a Pownd, a worse cannot bee conceived.” 2. Since then certain improvements had been made, perhaps ordered by Iskandar Muda, which made Beaulieu made the following comment in 1621, he mentioned about “a big round fortification from where one can directly watch the mouth of the river, and complemented by several cannons that could shoot the balls close to the water surface, and there are two encircling walls with positioning cannons.”

 In front of the fort the king had also built a kind of “recreational park with several ponds and beautiful foot paths”, “the entire place is encircled by a ditch and earth wall planted by grass of 10 to 12 feet high to protect 2 to 3 thousand people. In front of the protection ditch is a small fort which is covered by bushes and inside are some cannons” Beaulieu also mentioned that the striking feature about the fort is the mosque inside it.

However, the town itself was not protected by a fort wall. This surprised the European travelers who were accustomed with European forts. According to Beaulieu, this was because the surrounding natural environment was such that made it difficult for people to land, so there was a kind of natural protection. But another analysis said that Aceh at the time was a very big and mighty power with a great authority, which made it think unnecessary to defend itself from the neighbors. In Hikayat Aceh or the Chronicles of Aceh, it was mentioned that the arm’s elephants were the real fortification. However, to the North East, along the coast toward Pidir, near the go downs of galleon ships, several small forts had been built, at interval distances of a bullet gun, and each had two or three cannons. According to Beaulieu, those forts could not be seen because they were covered by bushes. De Graaf mentioned in 1641: “Outside the town are some fortifications where tunnels had been excavated in the land and there are several cast cannons, good ones, without carriages but located directly on the sand.”


Forts in the Dutch Indies (1817-1942)

(prepared by Hans Bonke)


In the eighteenth century, tens of VOC (the United East Indies Company) forts were found scattered around the archipelago. Most of them were in fact just fortified warehouses to store trade goods and supplies, office buildings and living quarters for the personnel. A number of forts, for example Vredenburg in Yogyakarta, were designated to visually express the Dutch political power. Such forts, constructed from stones, were built as a protection against indigenous enemies who had no weapons; therefore, the structures were not as strongly fortified as those in Europe. The castle of Batavia with its encircling wall, for example, was already more than a century old and in military terms, totally obsolete. The power of VOC was not in her forts but in her heavily armed ships that controlled the sea and could render assistance wherever and whenever demanded. That was also the reason why most forts were situated along the coast.

Fig. 2.Fort Vredeburg, at Yogyakarta


In the course of the eighteenth century, VOC lost her position as the most important sea power in Asia to the British. During the Fourth British War (1780-1784), a number of East-Indies ships were confiscated by the British causing stagnation in the trade activities in Europe. The huge amount of loss suffered during the war marked the beginning of the end of VOC.


At the same time, the company could barely manage the attacks from Buginese which occurred around Riau and Malacca. The Dutch government sent in 1784 the first of three squadrons of warships to Asia, with the objective to restore VOC’s damaged authority. The ships arrived just in time to relieve Malacca. From 1789 to 1793, a military team commissioned by the Dutch parliament inspected the fortifications located in VOC realm. The team’s detailed reports and suggestions were never executed because of political developments in Europe at the time.



In 1795, the French revolutionary armies occupied the Netherlands, terminating the Republic of the United Provinces. One of the first regulations issued by the new Republic of Batavia was to nationalize the bankrupt VOC. On December 31 1799, the company’s right expired and was not extended. All her belongings became state possessions. The Republic of Batavia, as an ally of the French, was automatically British enemy. Most areas possessed by VOC voluntarily or by force submitted themselves to the British. Java was still not occupied but the Royal Navy sank the last surviving warships. Invasion was just a matter of time.



Fig.3. H.W.Daendels, Governor General for Dutch Indies in 1808


In 1808 Daendels was sent as governor general from the Netherlands to Java. He was ready for a British invasion, but without a navy and with an army of only 6,000 men (4000 of them in Java), it was impossible for him to defend the whole archipelago. Daendels decided to limit the defense activities to West Java only where he preferred to defend the hinterland (the interior areas). When this plan seemed impossible to be executed, Daendels ordered the construction of a strong fortification at Meester Cornelis (Jatinegara), and increased his army to around 19,000 men. Surabaya became the new marine port, with Fort Lodewijk at Gresik controlling the strait between Java and Madura. The construction of a marine port at Meewen Bay in West Java was forced to be discontinued because of health reasons. The construction of a fort at Anyer, and the restoration of old VOC forts along the northern coast were completed. The British did control the sea, but because of the construction of the Great Post Road, it was still possible for Daendelds to move troops from Anyer Banyuwangi. In 1811, Daendels was recalled to Europe by Napoleon.


A few months later, British troops landed east of Batavia and defeated the Dutch-French army at Meester Cornelis. One month later the colony surrendered. The British paid small attention to the existing forts which were hardly maintained. It was more important for the British to capture the “kraton” (the indigenous palace) at Yogyakarta, by which a European army was able to directly interfere in the administration of a Javanese king.


Dutch Indies (1814-1942)

In 1816 the British transferred its authority over Java and the dependent regions to the Dutch. The state treasury was empty and the Dutch Indies colony had to deliver as much profit as possible to the motherland. In the first decade, the colony was just a money-losing post because the transfer of power didn’t take place smoothly. As a successor of VOC, the Dutch administration took it for granted that the local kings would honor all the previously signed agreements. Some of them did, but at most places, they refused to accept the old situation. A rebellion broke out at Saparua and Haruku, and Fort Duurstede was taken over by surprise. A punitive expedition ended the rebellion in 1817 with heavy bloodshed. In 1821, the sultanate of Palembang in Sumatra was defeated. In Borneo, Chinese companies refused to recognize Dutch authority, which necessitated the sending of a military expedition in 1821. Two years later, for the same reason, the sultanate of Bone in South Celebes was also conquered. Most military expeditions failed at their first attempts because the enemy was underestimated and the area insufficiently known. It was frequently necessary to send new military expeditions.

In Sumatra, the Dutch were involved in 1821 in the struggle of Minangkabau people against fundamentalist “Padris”, religious Islamic teachers. The war dragged on for years with alternating victories and losses, and the pinnacle was the 26-month beleaguering of Bonjol (the leader Padri). Conquering the last fortification of the Padri in 1838 ended the armed conflict.


Map of The Java War, 1825 - 1830

Prince Diponegoro



In 1825 a Great War broke out in Java against the Dutch led by the charismatic Prince Diponegoro. Initially, the Dutch colonial army was unable to effectively respond to the guerrilla war of the Javanese but the tables were turned when the Dutch began to employ small mobile army units and building more than a hundred small fortifications where the local people could live and conduct their trade activities undisturbed. By the application of what was called the benteng-system it was possible to continuously narrow the area for the guerrilla wars. The war ended in 1830 with the capture of Diponegoro and eventually Dutch authority in Java was definitively restored.



The Defense of Java against a European Enemy

Following the end of the Java War (1825-1830), the government of Dutch Indies decided to restructure her defense policy, dividing the colony into Java and the areas outside. Java remained the seat of the government as the most affluent island of the colony. The outcome of the Javanese war had proved that the colonial army was able to defeat an indigenous enemy. It was therefore considered not necessary to build new forts, and the existing ones were seen as sufficient.


Threats were expected from European enemies, which essentially meant the British who could send within a short time around 25,000 invasion troops to the Dutch Indies from India. The series of unrest in Europe gave reasons to governor general Van den Bosch (1830-1833) to propose a defense policy for Java originating from the interior areas, and to move the government seat out of the vulnerable Batavia into the interior area. On the flat north coast, Batavia, Semarang and the war port Surabaya were enforced with the objective to keep the enemy on the unhealthy northern coast. As the only good port at the south coast, Cilacap was also reinforced. As an extra defense against attacks from indigenous enemies, blockhouses were built at 7.5 to 15 km distances.


In 1834 the director of the army’s engineering department, Van der Wijck presented the following further detailed plans to protect Java against the British:

  • Defense would be conducted by a mobile army, so the number of fortifications could be limited;

  • The field army would retreat to a central position behind Toentang river where the central redoubt, the new Fort Willem I was located in Ambarawa;

  • Since the north coast was open and the enemy could land anywhere, the Great Post Road should be realigned along the interior area; along the road new forts were to be built in Bandung, Gombong, Ngawi and Melirup;

  • In Batavia, Semarang and Surabaya citadels and coastal fortifications were to be built, as well as a small fortification at Cilacap.

  • Funds were made available to execute the plans, on the condition that moving the government seat to the interior would be further studied.


Fort Willem I – Ambarawa

Fort Van Der Wijk - Gombong


In 1844, Mayor-General Von Gagem was posted from the Netherlands to the Indies with the task to look for a simpler defense system. On his visit, the citadels and batteries at Batavia, Semarang, Surabaya and the forts Willem I and Ngawi and the two coastal batteries at Nusa Kambangan (opposite Cilacap) were already or nearly completed. He criticised the plan and location of the fortifications but it was too late for him to conduct any possible changes. On the advice of Gagem, the fort at Gombong was not completed and the constructions of two other forts were also cancelled. By concentrating the defense in the interior areas, Cilacap became an important port and depot, and a big fort was consequently constructed in the city. The general also proposed that in time of war the government seat should be moved into the interior area.


Von Gagem’s most important proposals were followed, but moving the government seat in time of war was, due to psychological reasons, impossible. No decisions were made since the attention on defense had begun to diminish after 1860 because the chance of an attack by a foreign enemy became very remote. The Dutch Indies Army (KNIL) was instead requested to concentrate on spreading the government’s authority outside Java (see following).


Army commandant General Haga (1887-1889) proposed to concentrate the army in West Java, on the Bandung plateau, where the government seat was also proposed to be located. In East Java, only Surabaya navy port would be defended. The commission that further elaborated the plans came with the following report in 1892:

  • Batavia remained the government seat, but in time of war, the governor general would move to Bandung;

  • The centre of defense was West Java, where a landing by the enemy should be prevented at all cost, and in the event this failed, the war should be conducted in the interior area;

  • Fort Willem I and Cilacap were removed from the list of forts;

  • The navy was to be reinforced and Tanjung Priok was to be developed into the most important navy base.


For the time being, not much was changed. Under governor general Rooseboom (1899-1904) definite actions were made to construct the fortifications at Batavia, Tanjung Priok and the access roads into the Bandung plateau. Surabaya became definitely the most important navy base, and the ports of Sabang and Padang in Sumatra were also reinforced.


Expansion of the Colony

In 1816, the Dutch Indies consisted of Java, the Moluccas, Bangka and some areas spread out in Sumatra, Celebes, Borneo and Timor. Claims on other parts of the archipelago remained mostly on paper. The vague defined borders led to continuous tensions with other colonial powers. The construction of Fort Du Bus at New Guinea (Papua) in 1828-1835 was solely meant as a Dutch response on the rumors about British plans to build a settlement on the island.


Considerations should also be made to adventurous mavericks, of whom the most successful one was James Brooke who was crowned King of Sarawak in 1841. The border poles engraved with Dutch emblems that were put on remote islands were not able to prevent attacks and claims on the colony. The only option was to send military expeditions to actively exercise the government’s authority on the coastal areas of those islands; the interior parts of the islands would eventually follow.


Not everybody approved the territorial expansion. The colony should foremost provide profit and expansion of the Dutch authority was only possible by conducting expensive military expeditions. Governor General Van den Bosch (1830-1833) was sent to the Indies with the duty to make the colony a profit-producing region. He achieved that by severely cutting expenditures and introducing a forced cultivation system. He was also opposed to conduct further expansion of the Dutch authority outside Java and Madura. Expensive military expeditions to islands that didn’t deliver economic advantages were forbidden; nevertheless, power expansion to the outside regions continued. Not all government official followed Batavia’s policy. In Sumatra, general Michiels for example at his own initiative occupied the whole West coast of the island up to Aceh.


Under governor general Rochussen (1845-1851), for the first time since the Padrie war, a big operation was organized, “to combat coastal- and sea-piracies” in Bali. Since that time up to the beginning of the twentieth century, no year passed without the Dutch Indies Army being at war somewhere in the colony. During most of those military expeditions, (temporary) forts were built.




The Forts

When they returned to the Indies, the Dutch took up the former VOC forts; most of them were built from stones. A number of them were in most dilapidated conditions. From 1853 onwards, reviews appeared in the Dutch Indies Statute Book about the permanently manned forts in the colony that were classified into four categories.


Forts belonging to classes 1 and 2 were on Java and could provide defense against a European enemy. Forts belonging to the other two classes were solely meant to protect against indigenous enemies. The list was constantly updated with the construction of new forts and deletion of obsolete forts. In 1867, across the whole archipelago, there were the following 143 forts.



Forts in 1867






Java & Madura





































The plans of those forts built in Java to defend against European enemies differed only slightly with plans of forts built in the Netherlands, and they followed the same developments that occurred in the fortification building style in Europe. Fort Willem I in Ambarawa and the torture tower of the Marine Post at Onrust Island still followed the building tradition of European forts in the first half of the nineteenth century. The polygon fort of Cilacap (1864-1879) was built following a much modern concept, but when the fort was used, the weapon positioning became obsolete because of the development of high explosive shells. Hence, modern forts were built between 1905 and 1920 around Batavia and in the Preanger region (West Java). The building of “pantser”-type forts, such as those built since 1880 for the fortification of Amsterdam, came into consideration but was never executed.


Expansion of Dutch authority in the outer regions was accompanied by the building of forts that were meant to consolidate the control on the just acquired regions. The standard plan of the army’s engineering department was a small square fort with two diagonally located bastions with a cannon placed on a turning gun carriage. The walls were usually made from earth, complemented by a palisade and buildings made from wood or woven mats, with dried grass roofs. The forts were encircled by a moat, provided with mantraps made from broken glass, and after 1850, made from barbed wires to prevent surprise attacks. Such forts were built in many locations across the archipelago, in Bangka and Borneo, but mostly in Aceh.


In Aceh, between 1884 and 1896, the Dutch retreated within the so-called Concentrated Line, which was a ring of 16 forts. It was an inexpensive but not very effective way to continue the war. The Aceh war ended when the Dutch Indies Army left the forts and engaged in an effective counter-guerrilla war. The tropical climate hastened wood decay which necessitated the forts to be regularly repaired. It also regularly happened that due to the territory being unknown, the area around the forts would be inundated during the rainy season; forts would even be drifted away. One fort in Borneo had to be moved three times to different locations in ten years because of such reasons. Most of the forts were anyway of temporary nature and would be abandoned whenever order and peace were restored.


Van Heutsz in Aceh


It was Van Heutsz who as governor of Aceh ended this manner of building forts. He forbade the construction of palisades and walls that only gave a feeling of safety and instead ordered the use of barbed wires. Overall, outside Java only a small number of temporary wooden or earth forts that had been built during the time of colonial expansion were replaced by permanent forts made of stones. The new perspective on hygiene contributed to the view that the crammed housing within the forts was considered most unhealthy. The military were then moved to modern, more airy barracks.


After 1900, the whole archipelago was controlled by Dutch authority, and the construction of new fort against indigenous enemies was considered no more necessary. The Dutch Indies Army (KNIL) changed from a combat army into a police army.


Interbellum (Period between the World Wars): 1918-1939

After the First World War (1914-1918), Japan emerged as the biggest threat for the colony, considering that Japan would, through conducting small-scale attacks, seize the indispensable oil and other minerals. In the document titled Principles of Defense 1927 the Dutch Indies government laid out her basic principles of policy which was followed until the outbreak of the Second World War. The basic policy principles were:

  • The army and the navy keep order and peace within the colony;

  • At outbreaks of international conflicts, they would remain neutral;

  • Execution of the policy in Java would be the responsibility of KNIL with support from the navy, and in the outer regions, it would be the responsibility of the navy with the support of the army;

  • At most vulnerable locations, such as the oil ports of Tarakan and Balikpapan – even in peace time, additional troops were stationed to prevent enemy attacks. The garrison was responsible that sufficient time would be available to destroy all the oil installations and supply in the event of an enemy attack. Execution of the policy was influenced by expenditure reduction actions which were taken following the world economic crisis because of the stock exchange crash in 1929, and also by the progress of the air force as well as by the war in Europe that started in 1939.


War Preparations 1940-1942

Following the occupation of the Netherlands by the Germans in May 1942, enough funds were made available for the defense of the colony, and a number of orders were placed at foreign weapon factories. It was impossible to deliver all the war materials because of the huge international demand for weapons. The commander in chief General Ter Poorten took out the old cannons from the depots and placed them as coastal defense along Java. In West Java, west of Batavia and Bogor, fortifications were constructed complemented with gun carriages along the Cisadane River from Serpong to Tangerang and also at Leuwiliang. Along all the access roads leading to Bandung plateau, fortifications were built complete with bunkers, trenches and barricades. Cilacap, as the only good port at the South coast and access to Australia, was extra-heavily protected. The city was surrounded by bunkers, gun emplacements and trenches for tanks; the 19th century fort was again included in the defense system.



General Hein Ter Porten



In East Java, several scenarios pertaining to the attack on Surabaya were prepared. Batteries and coastal forts in Java and Madura protected the thoroughfare to the navy base. The North coast was provided with additional protection. On the South, West and East parts of the town, positions were erected with the objective to prevent attacks coming from the interior areas. The fortifications around the navy base were never attacked. Outside Java, except in Tarakan, Balikpapan, Ambon, Menado and certain oil installations and airfields, just a few permanent fortifications were built.


At the Japanese attack in 1942, the coastal batteries were unharmed because the Japanese landed far from the fortifications, or went around the positions. The only important exception was Tarakan where the defense actions conducted on 11 and 12 January 1942 provided enough time to destroy the oil installations. The coastal batteries sank two enemies mine sweepers.


During the occupation of Menado and Ambon, a number of constructed fortifications played quite an important role of defense; however, it was not possible to stop the Japanese attack. They landed on the night of February 28 – March 1, 1942 at three locations along the North coast of Java. The fortification located at Leuwiliang was defended by Australian troops against Japanese attacks; they then retreated towards Bandung. The fortification along the Cisadane River was not attacked. Batavia was declared an open city.


The Japanese troops, after landing at Kragan (?) in East Java, went up to Surabaya and reached the city after the surrender of Java. The defense structures around the city had played no role. The biggest threat to the government in Bandung came from Japanese troops who landed at Eretan Wetan in Central Java and had quickly taken over the airfield of Kalidjati. They broke two KNIL attacks and reached on March 5, the fortification at Ciater, north of Bandung. Because of this breakthrough, the road towards Bandung became made free for the enemy to conduct the attack. The Japanese threatened an air bombardment. KNIL capitulated.