The Spanish Inquisition was a significant and controversial institution established in the late 15th century and active well into the 19th century. It was a key component of the broader Inquisition movement within the Catholic Church, which aimed to combat heresy and enforce religious orthodoxy. The Spanish Inquisition, however, had distinct characteristics and a more intense impact than its counterparts in other European countries.

Background:
- In the late 15th century, Spain was united under the Catholic Monarchs, Ferdinand II of Aragon and Isabella I of Castile, who sought to consolidate their power. They believed that religious unity was essential for the stability of their newly unified kingdom.
Establishment:
- The Spanish Inquisition was officially established by a papal bull issued by Pope Sixtus IV in 1478, at the request of Ferdinand and Isabella.
- The Spanish crown appointed inquisitors who were responsible for enforcing religious orthodoxy and investigating heresy.

Targets:
- The primary targets of the Spanish Inquisition were conversos (Jews who had converted to Christianity) and moriscos (Muslims who had converted to Christianity). The Inquisition aimed to root out those who might be secretly practicing their original faiths.
Methods:
- The Inquisition used a combination of legal procedures and torture to extract confessions from suspected heretics.
- The accused often faced severe punishments, including imprisonment, loss of property, and even execution.

Expulsion:
- In 1492, the same year Christopher Columbus set sail for the Americas, Spain issued the Alhambra Decree, which ordered the expulsion of Jews who refused to convert to Christianity. This marked the beginning of the large-scale persecution and expulsion of Jews from Spain.
- In 1609, Spain also expelled the moriscos, effectively eliminating the Muslim population from the Iberian Peninsula.
Suppression of Dissent:
- The Spanish Inquisition was not limited to religious matters; it also sought to suppress political dissent and heretical ideas.
- The Inquisition’s reach extended to censoring books and ideas that were considered heretical, including works by Protestant reformers.
Decline:
- By the 18th century, the influence of the Inquisition began to wane. Enlightenment ideas and political changes in Europe contributed to a more tolerant atmosphere.
- In 1812, during the Peninsular War, the Spanish government abolished the Inquisition. Although it was later briefly restored, it was finally disbanded in 1834.
The Spanish Inquisition left a lasting impact on Spain and its colonies, contributing to the expulsion or forced conversion of Jews and Muslims and shaping Spain’s religious and political landscape. It was a symbol of religious intolerance and the power of the Catholic Church during the late medieval and early modern periods.