Air warfare is a tactic of military operations carried out using aircraft, either in the form of dog fights or attacks by aircraft against enemies on land, water or below. Air warfare is almost entirely a creation of the 20th century and has become an integral part of modern warfare. Even air warfare is one of the keys to success in military operations in modern warfare. In World War I (World War I) air power had an important role for the two warring parties, namely the Allied Bloc which was a combination of Britain, France, and Russia and the Central Powers, which consisted of Germany, Austria-Hungary., and Italy. Both blocs use air power primarily to gather intelligence visually through aerial observations as well as aerial photography [1].

During World War I, the potential and usefulness of reconnaissance aircraft for the military was so great that both sides mobilized all their air power to defeat the enemy reconnaissance aircraft. At that time, fighter aircraft was a type of aircraft that was less important. War aircraft were not capable of carrying bombs or gathering information. The function of the fighter aircraft was only to conduct air combat with opposing fighter aircraft escorting reconnaissance aircraft or bombers. But over time, fighter aircraft became essential because reconnaissance aircraft and bombers could not operate safely without the air superiority that only fighter aircraft could create. As a result, the two blocks competed to create more sophisticated fighter aircraft to gain air superiority. This competition has led to the rapid improvement of aircraft technology, not only from fighter aircraft but also to other types of aircraft [1]. Air power again played an important role in WW II, especially for carrying out strategic bombing of enemy military installations and distributing leaflets containing propaganda. Since this period, experts and practitioners of air warfare around the world agree that air superiority is a prerequisite for achieving victory in modern warfare. Countries in the world also began to strive to build air power to achieve air superiority over other countries for certain missions such as bombings, air support operations, reconnaissance, and regional defense [1]. The Dutch colonial government also began to build and use air power during the colonial period in Indonesia long bxefore the proclamation of independence on 17 August 1945. This effort was marked by the construction of military air bases in a number of areas, especially in Java, since the 1920s. The Dutch move was an effort to prepare themselves to face Japan, which was increasingly invading neighbouring countries, especially after the victory of the State of the Rising Sun over Russia in 1905. In the 1940s the Dutch had about ten air bases on the island of Java [2]. Air power is also an important element of the Japanese military in Indonesia. Even when they first attacked the Dutch colonial territory in the archipelago, one of the priorities of the Japanese army was to seize and occupy the Dutch’s air bases such as the air bases in Palembang, South Sumatra and Kalijati, West Java [3].

After winning over the Dutch in Indonesia, Japan then took over and used the former Dutch air bases for its military purposes [4]. The surrender of Japan to the Allies was followed by the statement of the Proclamation of Indonesian Independence on August 17, 1945 and the establishment of the People's Security Agency (BKR). Subsequently, BKR took over Japanese military and armament installations, including air bases and aircraft. Armed with aircraft and military air bases left by Japan, the Air BKR was formed which is the forerunner of the Indonesian Air Force [5].

During the power transition period, the Dutch tried to regain control of Indonesia by piggybacking on the Allied troops. This effort was rejected by the Indonesian people. Therefore, the BKR together with the people fought against the Dutch troops. One of them was by attacking the Dutch position through an air attack on July 29, 1947. The air attack operation was the first air warfare carried out by the Indonesian military after the independence. This research was conducted with the aim of knowing the strategies and impacts of air warfare in Indonesia in the past as a material for reflection and considerations on the potential use of air power in air warfare in the future.

The analysis in this study uses the historical review method based on the theory of the function of air power. According to Howell and Prevenier [6] regarding the historical review method, there are three important elements required to be considered, namely choosing reliable sources, reading these historical sources well, and conveying narratives about historical events in the past well. The criteria for reliable sources include the form and information provided and how historians have used these sources. The ability to read good sources is characterized by the ability to sort out information and interpret historical sources. While the ability to convey a good narrative is when one is able to provide knowledge about certain events in the past. In this study the authors carefully selected reliable historical sources such as academics, observers and practitioners of air power. The forms of data and information used include scientific publications such as books, journal articles and other data and information. Furthermore, the findings are presented with a chronological narrative accompanied by supporting data and logical arguments. This study uses the theory of the function of air power as coercive power as the lens of analysis. According to Pape [7] the use of air power as a coercive power against the opponent has four main strategies, namely punishment, risk, denial and decapitation. Based on the four typologies of strategies for using coercive power from air power, this study analyses air warfare during the struggle for independence, particularly the attack on the Dutch military in Semarang, Salatiga and Ambarawa on July 27, 1947. The analysis was conducted to reveal the type of coercive power strategy used as well as the impacts.

Air Power’s Coercive Power in Modern War

Many historical records show that often a country uses military force to impose its will on other countries. The coercive power possessed by a country's military power can often achieve its goals without incurring high risks, especially when carried out by a country that has a stronger military. Forced parties often have to surrender or comply with the will of the coercive state without engaging in war [8].

The most important military power commonly used in modern times is air power. As mentioned earlier, the coercive power of air power is exercised through four strategies namely punishment, risk, denial and beheading strategies. The punitive strategy is air strikes to attack civilian sectors related to the economy, such as electricity, water, or agricultural targets such as irrigation systems. The aim is to paralyze important economic pillars so that opposing civilians have difficulty carrying out their daily lives. This condition is expected to force the opposing side to stop the war. To achieve this objective, air campaigns were carried out as intensively as possible to maximize the effect of shock on the opposing party. A risk strategy is an air campaign that resembles a punitive strategy. The difference is that air strikes are carried out gradually and continuously but at an increasing tempo. Air strikes target from less important to more critical civilian targets. Air strikes will be temporarily suspended if there is a diplomatic signal from the opposing side to stop the war. Meanwhile, the refusal strategy uses air strikes to attack military targets and military production centers such as troops in the field, command headquarters, communication systems, and logistics. Denial missions generally require pinpoint accuracy so are generally carried out during the day if air superiority permits. The refusal strategy is executed with maximum intensity and may be repeated against important targets to prevent the opponent from being able to make improvements. The fourth strategy, namely beheading, is a combination of punishment and denial strategies simultaneously [7].

Air power began to be used for military purposes during World War I. When World War I broke out in July 1914, the aviation industry in the world, especially in Europe was still in its early stages of development. Aircraft technology and its use is still very limited. However, the countries involved in the war, both those belonging to the Allied and the Central Powers, have adopted the aerospace technology for military purposes. Air power at that time did not stand alone and was generally part of the army [9].

In September 1914, for example, French reconnaissance aircraft played a key role in detecting the movement of German troops to the Northeast of Paris. Based on this information the French and British managed to attack the German troops. On a tactical level, some artillery commanders also used reconnaissance aircraft to direct their bombings. Aircraft were also used to drop bombs on enemy troops. In November 1914, the French military began to consider strategic bombing of German industrial centers and began forming squadrons of bombers. The Central Powers also made aircraft one of the tools in the great war. Germany, for example, used Zeppelin aircraft for reconnaissance and bombing operations. In August and September four Zeppelin aircraft were assigned to reconnaissance and bombing missions against cities such as Antwerp, Zeebrugge, Dunkirk, Calais, and Lille. However, all four aircraft were eventually destroyed by the British in the bombing of Düsseldorf on October 8, 1914. German aircraft played an important role in reconnaissance operations on the Western and Eastern fronts. Aircraft are stated as a reliable means of information especially for confirmation. In addition, aircraft are also an important reconnaissance tool in various military operations and are an important part in the decision making of army commanders [9].

Such accounts demonstrate aircraft had an important role during World War I, namely as a very effective reconnaissance tool. In addition, although with limited technology and range, aircraft have also proven capable of supporting the military to carry out bombings against strategic targets in enemy areas. Military aviation did not determine the outcome of World War I, but they contributed significant role in supporting the army to achieve victory in World War I. Based on the typology of the coercive power strategy, the function of air power in World War I could be categorized as a denial strategy, namely to attack military targets of the enemy such as troops in the field, command headquarters, communication systems, and logistics.

Air power became an increasingly important part of the various battles of WWII. The two warring parties, namely the Allies and the Axis, again deployed their respective air powers with increasingly advanced technology. The Allies consisted of the United States (US), the Soviet Union, China, the United Kingdom, and France, while the Axis consisted of Germany, Japan, Italy, Hungary, Romania and Bulgaria. The US used air power primarily to control air space and provide fire support from the air to friendly troops on the ground. This air strategy gave Allied troops flexibility in their ground combat and guaranteed minimum interference from the German Air Force. US air power destroyed nearly all German air power (Luftwaffe) in the Mediterranean, both through dog fights and by attacking airfields and logistics bases. US air strikes also repeatedly cut off enemy’s air, sea, and land lines of communication, allowing the Allies to capture North Africa and Sicily and invade southern Italy. US B-29 bombers in the Pacific also played an important role in attacking Japan from bases in China. The peak use of Allied air power in World War II was when US bombers dropped atomic bombs on August 6 and 9, 1945, on Hiroshima and Nagasaki, Japan, respectively [10]. Germany also deployed an air force namely the Luftwaffe in WWII. German aircraft were used to attack allied aircraft and also to carry out strategic bombings, for example into British territory. However, the German power was less successful and even considered a failure, because the aircraft technology owned was still inferior to that of the Allies [11].

Based on the typology of the strategy of using coercive power in air power, the warring parties in World War II used two strategies, namely denial and punishment. Air attacks on military targets such as troops on the ground, communication systems, military industry, and logistics were a form of refusal to reduce the strength of the opponent or be destroyed so that they could not continue the war. Meanwhile, aerial bombing of civilians such as the dropping of atomic bombs on Hiroshima and Nagasaki was a punitive strategy.

The Gulf War in 1991 was the first modern war to demonstrate the use of a decapitation strategy by air power. In the war, the air power of the Coalition Forces was mainly used in the early days of the war to carry out strategic bombings to paralyze the government and military systems of the opponent, namely Iraq. The strategy was implemented by attacking the communication system network of Iraqi national political and military leaders. After the war began, another strategy that was prominently used was denial in the form of air strikes against military targets such as ground troops, protective bunkers, airfields and enemy logistics [7].

Air Force in the Colonial Period and the Birth of the Air Force

Air power also became an important part in the struggle to defend Indonesia's independence, which was proclaimed on August 17, 1945. Even though they had just declared independence, the Indonesian people soon had an air force with Japanese heritage aircraft and Dutch air bases as capital. The history of Indonesian air power began long before the proclamation of independence, which was started by the Dutch who tried to fly hot air balloons in 1890 in Batavia and Aceh. The Dutch colonial government began to utilize air power for military purposes since World War I broke out in 1914. This effort was marked by the establishment of two aviation agencies, namely Military Aviation (Militaire Luchtvaart / ML) in Kalijati and Marine Aviation Service (Marine Luchtvaart Dients / MLD) in Surabaya. The two agencies initially only provided flight training to the Dutch army. However, by looking at the situation in Europe, which was still under threat of war and the limited number of Dutch pilots, the Dutch finally gave the indigenous population the opportunity to be trained to become pilots. In 1937 as many as 10 young Indonesians had the opportunity to be trained as pilots in Kalijati, namely Sambujo Hurip, Adisucipto, Husein Sastranegara, Sulistyo, Murkijo, Suyono, Bajuri, Sunarto, Haryono, and Tugiyo. It was they who later became pioneers in the formation of the Indonesian Air Force in the early days of independence and contributed to the resistance against the Dutch in the first Military Aggression in 1947. In addition to the establishment of these two aviation agencies and the recruitment of indigenous people as pilots, the Dutch also increased the number of air fields in a number of areas. Initially, air fields were built in Bugis, Maguwo, Cililitan, Gorda, Maospati, Kalijati, Andir, and Cibeuruem. After World War I ended, the number of air fields grew rapidly, which spread along important routes connecting major cities. When Japanese troops attacked Dutch positions in March 1942, the Dutch actually had a fairly complete fleet of air force. The aircraft included a Glenn Martin bomber, a Curtiess Falcon and Lockheed 12 for reconnaissance, a Lockheed Loderstar carrier and a Koolhoven trainer aircraft. Dutch air power (ML) was able to provide fierce resistance to Japanese air power for three months. But it turned out that the Japanese were stronger and able to destroy almost all Dutch aircraft. The only two remaining aircraft were a Glenn Martin and a Lockheed. Both survived but were badly damaged and were taken to Australia after the Dutch declared being defeated by Japan. After accepting the defeat of the Dutch which was marked by the signing of the Kalijati Agreement on March 9, 1942, Japanese troops immediately took over Dutch control in the archipelago, including air fields. Japan then used the Dutch air fields for its military interests. Japanese air power during the occupation of Indonesia was quite large. This can be seen from the number of military aircraft left by the Japanese when they lost to the Allied forces on August 15, 1945. At the Bugis air field, Malang, for example, the Indonesian fighters managed to find and seize 105 aircraft and a number of air attack repelling weapons and other weapons. Of the 105 aircraft, 12 were in good condition and ready to fly. A number of 38 aircraft of various types belonging to Japan were also captured by the fighters at Morokrembangan air fields, Surabaya [12].

Armed with the aircraft from Japan, the Indonesian fighters then pioneered the formation of an air force which became the forerunner of the current Indonesian Air Force. The main capital used were ex-Dutch air fields and ex-Japanese aircraft. The fighters were facing difficult challenges due to the limited number of aircraft and supporting personnel such as pilots and technicians. At that time, there were more than a hundred aircraft of various types such as Nishikoreng, Cukiu, and Cureng trainer aircraft, Hayabusha and Sansikishin hunter aircraft, Guntai and Sakai bombers, and Nakayima reconnaissance aircraft. However, most were not in good condition and ready to fly. The number of fighters who were able to fly aircraft was also very limited, only those who had received flight training during the Dutch era. When the Japanese came to power, the natives were not trained to be pilots. However, a number of indigenous people were employed at Japanese air bases, for example as aircraft technicians so that they were able to repair the Japanese aircraft. After the proclamation of independence, the Preparatory Committee for Indonesian Independence (PPKI) held a session on August 22, 1945, the result of which was the establishment of the People's Security Agency (BKR). BKR consists of former members of the Defenders of the Homeland (PETA), Heiho, Kaigun, Keisatsutai, Seinendan and other groups of fighters. The existence of the air fields and aircraft left by the Japanese army then gave birth to the Air People's Security Agency (BKRO), which was organizationally under BKR. The air force pioneers who were members of the BKRO were mostly former members of the ML, MLD and VVC. The Voluntary Aviation Corps (Vriijwillig Vliegers Corps / VVC) was a military aviator recruited and trained by the Dutch to face the Pacific War [13]. On October 5, 1945 BKR changed to the People's Security Army (TKR) so that BKRO also adjusted to become TKRO [12]. With this minimal capital the fighters used air power in the struggle to defend Indonesia's independence. Various kinds of air operations were carried out against the Dutch. One of them was air operations to bomb Dutch military headquarters in Ambarawa, Semarang and Salatiga, on 29 July 1947.

Air Strike Operations on 29 July 1947: Offensive Strategy and Impact

One of the contributions of the air fighters after the proclamation of independence that had a considerable impact and became part of the important historical record of the war of independence was the air strike operation against the Dutch military headquarters on July 29, 1947. The air fighters made as sudden attack to the Dutch military headquarters in three cities, namely Ambarawa, Salatiga and Semarang after the Dutch unilaterally canceled the results of the Linggarjati agreement.

When Japan lost the war to the Allies, the Dutch tried to re-colonize Indonesia. The Dutch did not want to recognize the independence of Indonesia which was proclaimed on August 17, 1945. As a result, the Dutch got resistance from the Indonesian people everywhere. But then the two sides entered into a ceasefire and negotiated in Linggarjati, West Java. In these negotiations, the Dutch and the Republic of Indonesia agreed to sign an agreement known as the Linggarjati Agreement on March 25, 1947. In the agreement the Dutch recognized that the territory of the Republic of Indonesia was covering Sumatra, Java and Madura. In addition, the Dutch was also willing to immediately leave the territory of the Republic of Indonesia no later than January 1, 1949 [13]. However, the Dutch broke its promise and unilaterally cancelled the agreement on July 21, 1947 by deploying its military forces to attack and occupy various Indonesian territories in Sumatra and Java [14].

The Dutch military attack was known as Military Aggression I. The first targets attacked by the Dutch were Indonesian air bases in Java, from West to East, from the Gorda air base (Banten, West Java) to the Pandanwangi air base (Lumajang, East Java).). The Dutch used military air power to attack and destroy the newly formed Indonesian air power with machine guns, bombs and rockets. As a result, most of the TKRO aircraft were destroyed or badly damaged. For example, from the Maguwo air base, of the 40 aircraft, only four survived after the Dutch air strike that day, namely two Cureng trainers, one Guntai bomber, and one Hayabusha fighter plane [12].

Attack Strategy

Soewito et al. [12] in the book “Awal Kedirgantaraan di Indonesia: Perjuangan AURI 1945-1950” (The Beginning of Aerospace in Indonesia: the Struggle of the Indonesian Air Force 1945-1950) said that the air attack from Dutch military aircraft on the Maguwo air base caused anger among the fighters, including the flight cadets at the Maguwo Aviation School. They therefore expressed a desire to retaliate despite realizing that most of the aircraft had been damaged. At the same time the technicians were secretly repairing or modifying several aircraft for this purpose. Several flight cadets who wanted to carry out the counterattack included Bambang Saptoaji, Suharnoko Harbani, Sutarjo Sigit, and Mulyono. The request was then conveyed to the Deputy Operations for the Air Force Chief of Staff, Air Commodore Halim Perdanakusuma. Because it was not within his authority to decide, he invited one of the cadet representatives, namely Suharnoko Harbani, to report to the Air Force Chief of Staff, Air Marshall Suryadi Suryadarma, regarding the proposal. The Air Force Chief of Staff did not approve the counter-attack plan because their status were still cadets. They were allowed to involved in such operations. However, due to the persistence of cadet Suharnoko Harbani, Air Marshall Suryadi Suryadarma finally decided to allow them to use existing aircraft and bombs to attack the Dutch, provided that the Air Force Chief of Staff neither order nor prohibit the air attack operation.

On July 28, 1947 at 20.00 Western Indonesia Time, four pilot cadets, namely Bambang Saptoaji, Suharnoko Harbani, Sutarjo Sigit, and Mulyono were ordered to appear before the Air Force Chief of Staff. During the meeting it was decided that a counterattack against the Dutch was necessary. The main purpose of the attack was to increase the morale of the fighters against the Dutch who wanted to re-colonize. The Air Force leadership reminded again that the air strike was not an official operation on orders from superiors but a voluntary act on the cadets' own initiative. Then Air Commodore Halim Perdanakusuma briefed the air attack plan including the targets, aircraft and weapons used, the personnel involved and the time of execution. The targets to be attacked were Dutch military installations in Semarang and Salatiga. For this purpose, the cadets would use four aircraft in Maguwo. At that time, there were only four aircraft that survived the previous Dutch attack, namely one Guntai bomber, one Hayabusha fighter training plane, and two Cureng basic training aircraft. The main weapon used was a fragmentation bomb weighing 50 kilograms. There were ten bombs used, namely six bombs on the Guntai plane and four bombs for the two Cureng aircraft. In addition to bombs, the Guntai and Cureng aircraft also attacked using machine guns. Hayabusha's aircraft would attack with machine guns and carry no bombs.

In the attack operation plan, pilot cadets Sutarjo Sigit and Suharnoko Harbani were tasked with attacking the Dutch in Salatiga with the Cureng basic training plane. The aircraft had been modified so that it could carry two bombs each on its wings. The first plane was crewed by cadet Sutarjo Sigit and gunner Sutarjo and the second plane was crewed by cadet Suharnoko Harbani accompanied by gunner Kaput. The Guntai plane, which was manned by cadet Mulyono and gunner Dulrachman, was tasked with attacking the Dutch in Semarang along with cadet Bambang Saptoaji who was flying a Hayabusha aircraft. However, in the end, cadet Bambang Saptoaji did not leave due to technical problems with the aircraft, so only Guntai aircraft were used to attack the Dutch position in Semarang. The attack time is set in the morning with a take-off time of 05.00 Western Indonesia Time.

In the morning of July 29, 1947, at exactly 05.00 Western Indonesia Time, three aircraft, namely two Cureng and a Guntai, took off towards the target. The Guntai aircraft, flown by cadet Mulyono and gunner Dulrachman, made the first take off to attack the Dutch in Semarang. Then the Cureng aircraft, manned by cadet Suharnoko Harbani, accompanied by gunner Kaput, followed his departure for Salatiga. The second Cureng aircraft crewed by cadet Sutarjo Sigit and gunner Sutarjo left last for Salatiga.

Cadet Mulyono who was flying the Guntai aircraft managed to take off smoothly and headed straight for the target in Semarang. Likewise with cadet Sutarjo Sigit who could directly take the Cureng to Salatiga. However, cadet Suharnoko Harbani experienced a few technical problems after take off and finally improvised changing the target by attacking the Dutch in Ambarawa.

In general the attack went smoothly. Cureng piloted by cadet Suharnoko Harbani managed to drop a bomb in the parking lot of the Dutch headquarters in Ambarawa. The explosion of the bomb was very surprising and caused panic in the Dutch army. Immediately after the explosion all the lights in the city immediately went out. According to the operation plan, cadet Suharnoko Harbani then immediately flew back to Maguwo. Cadet Sutarjo Sigit and rear gunner Sutarjo who flew with Cureng also managed to drop a bomb on the Dutch headquarters in Salatiga. The bombs they dropped were two fragmentation bombs and a number of incendiary bombs. According to Maharani [15] the target of the bombing was the Dutch military headquarters in the Ngebul area, Salatiga, which was the headquarters of artillery troops as well as a warehouse for the weapons. Currently the place is the headquarters of the 411^th Infantry Battalion of the Army Strategic Reserves Command of the Indonesian Army.

The plane returned to Maguwo as soon as the attack was over. The attack on the Dutch headquarters in Semarang by cadet Mulyono and rear gunner Dulrachman was also quite successful. They succeeded in dropping a bomb weighing 400 kilograms and shooting machine guns at the Dutch headquarters in Kalibanteng, Semarang. The Dutch army were panicked and a number of its pilots ran to the Kalibanteng air base to fly aircraft there to pursuit the attacking aircraft. The attempt was unsuccessful because their aircraft needed time to warm up the engines. One of the Dutch pilots was reckless and attempting to fly an aircraft whose engine was not hot enough. The consequence was fatal. The plane crashed at the end of the runway because it failed to take off. Finally, cadet Mulyono managed to fly back to Maguwo safely and free from the pursuit of enemy aircraft [12].

The Impacts of the Attack 

The air attacks carried out by the three Indonesian aircraft targeted the Dutch military headquarters. According to the theory of the use of coercive power through air power, the attack is categorized using a denial strategy, namely attacking enemy military forces such as troops in the field, headquarters, or logistics. The goal is to weaken or destroy the enemy's power so that they cannot continue the war. Although the purpose of the denial strategy is to force the enemy to stop continuing the war, the application of this strategy by Indonesian air fighters has little difference with the theory put forward by Robert A. Pape. According to Pape, the denial strategy can be used to force the enemy to stop the war by destroying elements of their military power such as troops in the field, command headquarters, or logistics.

This is slightly different from the way the Indonesian fighters carried out the air strike on July 29, 1947. Indonesian air power was indeed used to attack the Dutch military forces, namely headquarters and logistic warehouse. In theory, the air strike uses a denial strategy because it attacks enemy military targets. However, the attack was not aimed at destroying elements of the Dutch power in the designated cities. The Air Force leadership and the cadets on duty were well aware of this from the start. With very limited air power, namely three aircraft equipped with weapons of ten bombs, several incendiary bombs and machine guns, it was certainly impossible to destroy the Dutch military power. However, the end goal remained the same, namely to force the Dutch to stop the war. Then how could such a small attack be able to force the Dutch to stop the war?

Here we can see the ingenuity of the leaders of the Air Force and the Indonesian fighters at that time in determining the strategy. They used a denial strategy in the attack to force the Dutch to stop the war indirectly. It was indirectly because it was not done conventionally, namely by destroying elements of the enemy's military power. The goal was to destroy the enemy's military power so that it could not continue the war.

Although the attacks on the Dutch military forces in the three cities were aimed at the Dutch military forces, they did not aim to destroy them. The leaders of the Indonesian Air Force realized that the aircraft and weapons used were so limited that it was impossible to destroy the Dutch forces. However, the attacks are still carried out with other purposes. There are two goals to be achieved. First, the air attack was used to inflame the spirit of the fighters to remain optimistic and enthusiastic in fighting the Dutch. Second, the attack was used as a means to show the international community that the Indonesian army was still there and strong enough to fight the Dutch in order to attract sympathy and recognition for the independence of the Republic of Indonesia. Regarding the level of success in achieving the first goal, namely increasing the morale of the fighters against the Dutch, this is indeed difficult to measure. However, history records that the fighters never gave up in defending independence, both against the Dutch in Military Aggression I and Military Aggression II. The limitations of weapons and other military equipment did not reduce the courage and determination of the fighters all across of the country against the well-armed Dutch army. The fighting spirit and great determination might also have been inspired by the pilot cadets who bravely attacked the Dutch military headquarters, even though they only used ex-Japanese aircraft that had been repaired modestly.

The second objective, namely to show the international world the existence of the Indonesian army against the Dutch and to attract sympathy and recognition for the independence of Indonesia, proved successful. This happened because the attack became the topic of foreign media coverage. Radio Singapore, for example, made the air strike in Semarang, Salatiga, and Ambarawa one of the main news stories to attract international attention. The news attracted the attention of the international community and forced the Dutch to give an official statement on the attack. Although the Dutch official statement downplayed the attack, the appearance of the official statement proved the magnitude impact of the attack, especially for Indonesian diplomacy in internationally [16].

The attention of the international community towards the attack eventually also became one of the reasons for the objections from a number of countries such as the US, Britain, Australia and the Soviet Union to the Dutch’s Military Aggression I. With the support of these countries, the United Nations issued a resolution calling for a ceasefire to be implemented on August 4, 1947. Indonesia and the Dutch finally agreed to end the war on January 17, 1948, which was marked by the signing of the Renville Agreement [17].

Analysis of the use of coercive power by means of air power in attacks against the Dutch forces in Ambarawa, Salatiga and Semarang shows that the denial strategy carried out in the air strike was quite successful and achieved its objectives well. The air attack on the Dutch military forces in Semarang, Salatiga and Ambarawa carried out by the cadets on 29 July 1947 was not a major attack. The short air strike with three ex-Japanese aircraft did not physically cause any significant damage. However, what the three aircraft did had a very significant impact on the struggle of the Indonesian people.

The air attack was believed to have further boosted the morale of the Indonesian fighters against the Dutch and at the same time showed the Dutch that the Indonesian military was strong enough to fight back. How could it not be, within the limitations of the Indonesian Air Force which was only a year old, the aircraft which was still under construction and the flying school in such a limited condition were able to carry out an attack mission that greatly surprised the Dutch. Since the attack the Dutch began to turn off the lights at night throughout Central Java [18].

Another important impact of the air attacks was the strengthening of Indonesian international diplomacy in the struggle for recognition of sovereignty after the proclamation of independence on 17 August 1945. The UN resolution ordering a ceasefire had forced the Dutch to stop the war and sit at the negotiating table with Indonesia. This situation was politically favorable to Indonesia because it means that Indonesia had been explicitly recognized as a sovereign country which had an equal position with the Dutch. Although the results of the Renville agreement did not satisfy both parties and were soon violated again unilaterally by the Dutch, the agreement became one of the important milestones in the war to defend Indonesia's independence.

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