The Battle of Surabaya (Javanese: ꦦꦺꦂꦠꦺꦩ꧀ꦥꦸꦫꦤ꧀ ꦯꦸꦫꦧꦪ; Indonesian: Pertempuran Surabaya) was a major battle in the Indonesian National Revolution fought between regular infantry and militia of the Indonesian nationalist movement and British and British Indian troops against the re-imposition of Dutch colonial rule. The peak of the battle was in November 1945, and was the largest single battle of the revolution and became a national symbol of Indonesian resistance. Considered a heroic effort by Indonesians, the battle helped galvanise Indonesian and international support for Indonesian independence. 10 November is celebrated annually as Heroes' Day (Hari Pahlawan).
By the time British forces arrived at the end of October 1945, the Pemuda ("youth") foothold in Surabaya was described as "a strong unified fortress". Fighting broke out on 30 October after the British commander, Brigadier A. W. S. Mallaby was killed in a skirmish. The British retaliated with a coordinated sweep that began on 10 November, under the cover of air attacks. Although the colonial forces largely captured the city in three days, the poorly armed Republicans fought for three weeks, and thousands died as the population fled to the countryside.
Despite the military defeat suffered by the Republicans and a loss of manpower and weaponry that would severely hamper Republican forces for the rest of the revolution, the battle and defence mounted by the Indonesians galvanised the nation in support of independence and helped garner international attention.
For the Dutch, it removed any doubt that the Republic was not simply a gang of collaborators without popular support. It also convinced Britain that wisdom lay on the side of neutrality in the revolution; within a few years, in fact, Britain would support the Republican cause at the United Nations.
On 17 August 1945, Sukarno and Hatta declared the independence of Indonesia in Jakarta, two days after the Japanese emperor's surrender in the Pacific. As the news about the independence declaration spread throughout the archipelago, ordinary Indonesians felt a sense of freedom that led most to regard themselves as pro-Republican. In the following weeks, power vacuums existed, both from outside and within Indonesia, creating an atmosphere of uncertainty, but also one of opportunity. On 19 September 1945, a group of Dutch internees supported by the Japanese raised the Dutch flag outside the Hotel Yamato (formerly Hotel Oranje, now Hotel Majapahit) in Surabaya, East Java. This provoked nationalist Indonesian militia, who overran the Dutch and Japanese and tore off the blue part of the Dutch flag, changing it into the Indonesian flag. The leader of the Dutch group, Ploegman, was killed because of mass anger.
The senior Japanese commander in Surabaya, Vice Admiral Shibata Yaichiro, threw his support behind the Republicans and gave Indonesians ready access to arms. On 3 October, he surrendered to a Dutch Navy captain, the first Dutch representative to arrive. Yaichiro ordered his forces to hand over their remaining weapons to the Indonesians. The Indonesians were expected to hand them to the newly arrived Dutch forces, but did not do so.
The Nederlandsch-Indische Civiele Administratie (Netherlands Indies Civil Administration; NICA), which was part of the Royal Netherlands East Indies Army (Dutch: Koninklijk Nederlands Indisch Leger; KNIL), arrived in September 1945, with the intention of performing basic governmental duties, until the pre-war colonial government could be reinstated. In the meantime, British commanders had become preoccupied with the increasing boldness and apparent strength of the nationalists, who attacked demoralised Japanese garrisons across the archipelago with rudimentary weapons such as bamboo spears to seize their arms. The "bamboo spear" monument is still a common feature in Indonesian cities, e.g. Jakarta, Surabaya, and Pontianak. The main goals of British troops in Surabaya were seizing weapons from Japanese troops and Indonesian militia, taking care of former prisoners of war (POWs), and sending the remaining Japanese troops back to Japan.
In September and October 1945 a series of incidents took place involving pro-Dutch Eurasians, and atrocities were committed by Indonesian mobs against European internees. In late October and early November, the leadership of the mass Muslim organisations Nahdlatul Ulama and Masyumi declared that war in defence of the Indonesian motherland was holy war, and thus an obligation for all Muslims. Kyai and their students began to stream into Surabaya from Islamic boarding schools throughout East Java. The charismatic Bung Tomo made use of local radio to encourage an atmosphere of fanatical revolutionary fervor across the city. Six thousand British Indian troops were sent into the city on 25 October to evacuate European internees and within three days fighting began. After heavy fighting between the British Indian forces and around 20,000 Indonesian armed regulars of the newly formed People's Security Army (TKR) and mobs of 70,000–140,000 people, the British flew in the influential President Sukarno, Vice-President Hatta, and the minister Amir Sjarifuddin, and a ceasefire was achieved on 30 October.
On 26 October 1945, Brigadier A. W. S. Mallaby reached an agreement with Suryo, the Republic of Indonesia's governor of East Java, that the British would not ask Indonesian troops or militia to hand over their weapons. An apparent misunderstanding about the agreement between British troops in Jakarta (led by Lieutenant General Sir Philip Christison) and Mallaby's troops in Surabaya was to have serious ramifications.
Initially, British troops in the city comprised some 6,000 lightly armed British Indian soldiers from the 49th Infantry Brigade of the 23rd Indian Division. When the battle reached its peak, the British sent in additional troops which consisted of 24,000 fully armed soldiers from the 5th Indian Division, 24 US M4 Sherman medium tanks, along with a similar number of M3 Stuart light tanks, 24 battle-ready aircraft, together with two British Royal Navy cruisers and three accompanying destroyer escorts.
Indonesian forces consisted of 20,000 soldiers from the newly formed Tentara Keamanan Rakyat (TKR; People's Security Armed Forces) from its East Java Regional Command and an estimated 100,000–120,000 irregulars and militias. The TKR was formed partly by the former members of PETA, a semi-military organisation of volunteer cadre during the Japanese occupation and a few local officers of the former KNIL. The irregulars consisted of pro-Independence mobs, armed with rifles, swords, and bamboo spears. Some of their weapons were taken from surrendered Japanese troops.
On 27 October 1945, a British plane from Jakarta dropped leaflets over Surabaya urging all Indonesian troops and militia to surrender their weapons. The leaders of the Indonesian troops and militia were angered, seeing it as a breaking of the agreement reached with Mallaby earlier. On 28 October 1945, they attacked the British-Indian troops in Surabaya after cutting off all water supply to the British-occupied area. On 30 October the British flew Sukarno (president of RI), Hatta (the vice-president of RI), and Amir Syarifuddin Harahap (the minister of information of Indonesia) into Surabaya to possibly negotiate a cease fire. A ceasefire was negotiated with Major General Hawthorn (the commander of the 23rd British Indian Division) and Mallaby and immediately adhered to. Fighting, however, soon recommenced due to confused communications and mistrust between the two sides, leading to the outbreak of the battle.
On 30 October 1945, Brigadier Mallaby, the British brigade commander in Surabaya, was travelling about Surabaya to spread the news about the new agreement to his troops. At this time, Mallaby's team were forbidden to carry
any weapons except hand grenades. Later while patrolling, they received information that there was a mass of Indonesian militia advancing to the International Bank near Jembatan Merah (the "Red Bridge"). The team headed to the area but were trapped by shooting between Dutch soldiers who guarded the bank and local militias. When his car approached the British troops' post in the International building near the Jembatan Merah, it was surrounded by Indonesian Republican militia. Shortly after, Mallaby was shot and killed by the militia under confused circumstances.