Why did the spanish use the mission system in its northern territories? responses O the church was more interested in conquering the americas than the spanish monarchy church was more interested in conquering the americas than the spanish monarchy was. O missions were easy to expand into thriving towns and cities that would serve as military outposts. O it was impractical to send large numbers of settlers to distant lands, so the mission was used to establish control. O american indians always welcomed missionaries but resisted other spaniards.