The war of the Indian Sultanates, 1503-1534, saw the European powers starting to exert more influence in the east Indies, as they propped up Hindu states against the rise of muslim sultanates, influenced and backed by the strong Muslim trade that existed in the region. The kingdoms of Portugal and Spain put aside their differences to further their interests against the hostile states. In the Treaty of Seville, 1528, the two powers agreed on their respectively spheres of influence in the area, thereby avoiding conflict.
The war of the Indian Sultanates began with the seizure of the Malaccan straits, the core of the Malaccan Sultanate, and the expulsion of their leader, by Afonso de Albuquerque in 1503. European explorers and traders had already been hostile to rival muslim trading interests they had met in the far east and India, but this was the largest conquest yet seen of a Muslim state.
Then in 1512 and important development took place in the form of Prabu Siliwangi, the King of Sunda on Java, a Hindu kingdom under considerable pressure from the rise of neighbouring Muslim sultanates, appealed to the Portuguese at Malacca, even sending his son the crown prince to trade pepper and discuss terms. A padrao was eventually erected in 1516 and formal relations established, with a Portuguese garrison in the Ciliwung river.
From here the Portuguese raided Muslim trading interests at Cirebon, further incensing the sultanates. However, the close relationships between the Hindu kings of Sunda and the Sultan Sunan Gunungjati of Cirebon precluded an all out war at this point.
Conquest of Java
It was only when Sunan Gunungjati's son Hasanudin attempted to support the fledgeling Sultanate of Banten that war escalated between the Portuguese and the Sultanates. At sea, the European ships proved far superior and easily took control of the north coast, pushing forward to Cirebon itself. The Battle of Banten in 1525 was pyrrhic victory for the Portuguese, with Hasanudin's forces hold off their siege for months before an disease wiped out resistance. Hasanudin was sent to the court of his relation King Surawisesa of Sunda as a form of imprisonment. However escaping, he joined the defence of Cirebon, then also under blockade by the Portuguese. The Siege of Cirebon, 1526, was a decisive victory for the Portuguese, who sacked the city and crippled the network of Muslim traders in western Java. Hasanudin was killed in the fighting. Only the Sultanate of Demak remained. However the rising power of Portuguese and their harsh treatment of the defeat Muslims, made the crown of Sunda reappraise the real threats to its authority in the region. Demak held out until 1528, but with its fall to Portuguese and Spanish mercenaries in May of that year, Sunda expelled Portuguese traders from its realm and declared war, along with the Sultanate of Johor, the successor kingdom to the defeated Sultanate of Malacca.
Treaty of Seville 1528
Their corroboration during the siege of Demak, drew the Spanish closer to the Portuguese, between whom relations had been particularly strained in the preceding decade. Attacks on each other's shipping in China, Japan and around the Spice islands of Ternate and Tidore had left war a real possibility. This all changed with the Treaty of Seville in 1528, where King John III of Portugal and Charles V reaffirmed their alliances to one another and agreed to pursue the war in the Indies together.
1528-1534 and the Fall of Aceh
The Sunda kingdom was quickly brought into line, with a joint Iberian blockade of the coast, while an army of conquistadors from both kingdoms under the command of Diogo De Coimbra attacked the capital. After bloodily defeating the king's personal defence, they exiled him from Java and replaced him with his cousin Ratu Singa Siliwangi.
Meanwhile a Portuguese squadron under João Leiria finally took complete control of the Bintan islands and the coastal regions of the Malay peninsula, driving the sultan further inland and away from the lucrative spice trade ports.
The last Sultanate to fall was the fiercely independent Sultanate of Aceh, which had been mounting raids on Christian, Muslim and Hindu shipping in the previous decades. A combined force of conquistadors again landed at the capital Kutaraja and quickly took control. However, many of the pirates who had based themselves in Aceh merely moved home, and the raids on shipping in the region remained rampant for many years.