Spanish–Moro conflict
The Spanish initiated the conflict by conquering the Philippines and invading Moro territory in an effort to subjugate the region to their rule since the 1500s. When the Spanish conquered the Muslim Kingdom of Maynila, a vassal of the Sultanate of Brunei, the Islamic rajah, Rajah Sulayman resisted the Spanish. Manila then became the capital of the Spanish Philippines after the conquest, with the Spanish forcibly converting people to Catholicism. The Spanish–Moro Wars started with the Castille War, a war between Spaniards and the Sultanate of Brunei. (The term "Moro" at this time included Muslim Tagalogs who were ruled by the Sultanate of Brunei).
Sovereignty of the Philippines
On April 27, 1565, Spanish Conquistadores attacked the defiant Rajah Tupas, who had succeeded Rajah Humabon as king of Cebu. Tupas was defeated and made to sign an agreement after his defeat, effectively placing the Philippines under Spain. On February 8, 1597, King Philip II, near the end of his 42-year reign, issued a Royal Cedula instructing to Francisco de Tello de Guzmán, then Governor-General of the Philippines in severe terms to fulfill the laws of tributes and to provide for restitution of ill-gotten taxes imposed on the natives. The Cedula also decreed an undertaking by which the natives (referred to as "Indians"), "... freely render to me submission." The decree was published in Manila on August 5, 1598. King Philip died on 13 September, just forty days after the publication of the decree, but his death was not known in the Philippines until middle of 1599, by which time a referendum by which the natives would acknowledge Spanish rule was underway. With the completion of the Philippine referendum of 1599, Spain could be said to have established legitimate sovereignty over the Philippines.