 Upon the return of Adelantado Miguel López de Legazpi in 1565, and the establishment of the Spanish colonial government first in Cebu, then in Iloilo and finally in Manila, the island of Basilan was gradually colonized and settled, inducted as a Spanish possession as early as 1636, formally organized as the 6th District of the Police-Military Government of Mindanao by 1860, and completely pacified by 1886 - a period spanning exactly 250 years.In September 1581, Msgr.Domingo de Salazar, O.P., the first bishop of the islands, arrived in Manila.