What technique did the Spanish use when conquering new empires (like they used with the Muslims)

They introduced the concept of Reconquista to their people

Explanation:

Reconquista is a form of romanization that was associated with introducing Spanish national's identity all across the world.

After every conquests, Spanish empire often forced the conquered people to follow the Catholic religion. Spanish government at the time used this as a tactic to gained supports from its people.

Rather than telling them they're conquering a certain territory for economic benefit, they make the people believe that they're doing it to spread God's will. This belief/perception made the soldiers became more likely to made sacrifice during the war and bring crucial; victories for the Spanish empire

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