As medieval kings of León, Castile and Aragon were often unable to maintain public peace, protective municipal leagues began to emerge in the twelfth century against bandits and other rural criminals, as well as against the lawless nobility or mobilized to support a claimant to the crown. These organizations were individually temporary, but became a long standing fixture of Spain. The first recorded case of the formation of an hermandad occurred when the towns and the peasantry of the north united to police the pilgrim road to Santiago de Compostela in Galicia, and protect the pilgrims, a major source of regional income, against robber knights. With the countryside virtually everywhere effectively in the hands of nobles, throughout the High Middle Ages such brotherhoods were frequently formed by leagues of towns to protect the roads connecting them. The hermandades were occasionally co-opted for dynastic purposes. They acted to some extent like the Fehmic courts of Germany. Among the most powerful was the league of northern Castilian and Basque ports, the Hermandad de las Marismas: Toledo, Talavera, and Villa Real.
As one of their first acts after the War of the Castilian Succession, Ferdinand and Isabella "brought peace by the brilliant strategy of organizing rather than eliminating violence;" they established a centrally organized and efficient Holy Hermandad (Santa Hermandad) with themselves at its head. They adapted the existing form of the hermandad to the purpose of creating a general police force under the direction of officials appointed by themselves, and endowed with large powers of summary jurisdiction, even in capital cases. The rough and ready justice of the Santa Hermandades became famous for brutality. The original hermandades continued to serve as modest local police units until their final suppression in 1835.
 Early formation
The hermandades initially began to form in Andalusia in 1265, in towns seeking to “defend their interests” from Islamic rebels who had been taking land and proclaiming their leader king. The groups may have been inspired by a previously-existing Islamic police force called the Shurta. The hermandades worked as local militias to protect the towns they came from. Hermandades also curbed the actions of bandits and other criminals, becoming a kind of police force. As the hermandad gained more legitimacy, they also gained more powers and responsibilities. Along with working as a police force and militia, they also collected taxes, acted as judges, and worked with the Cortes and corregidores on these and similar administrative problems. The hermandad judges relied on the backing of the corregidores for legitimacy. The hermandad were given jurisdiction over a wide range of crimes including: "crimes on roads or in unpopulated areas; rape of honest women; blasphemy; and the passing of false money."
 Relationship with rulers
The hermandad have had an inconsistent relationship with the ruling powers of Spain. They were sometimes used to undermine the authority of the king or his officials, and sometimes used to enforce it. While under the reign of Isabella I of Castile they were used to consolidate her authority and silence those who objected to her reign, even against her ordinances for them not to do so. Early in their formation, they tended to be temporary and to work in favor of royal authority in times of unrest. The king also took only a very minor role in the formation and regulation of the league.
Under the reign of King Alfonso in 1298 the hermandad were used against the king because some of the towns felt that he had been abusing his power. This contrasts with the way the Hermandad sought to
When the country was operating under a regency the hermandad, in cooperation with one of the towns, wanted to keep the town in the best condition possible in order to better serve the future king’s needs. Under the rule of Isabella, the hermandad were used to strengthen centralized power, and were given much more power and legitimacy in order to do so. Some of the proof for this is in the changes in the balances of power between the hermandad and the Cortes and the Corregidor. At one point, the corregidores began to lose the respect of the people because they were unable to do anything about the outrages and abuses of power on the part of the hermandad. The corregidores were able to hold posts within the Holy Brotherhood, but their power was limited as was their power to control the Brotherhood from the outside. After the hermandad had been made official by Isabella and Ferdinand, creating the Santa Hermandad (also called the Holy Brotherhood), the hermandad gained a great deal of power. By 1476, the administration of the “soon-to-be-kingdomwide league was incorporated into Isabella’s government as the Holy Brotherhood”. Lunenfeld argues that the hermandad incorporated very tightly into the government to create a higher degree of centralization.
 Relationship with Towns and Local Communities
Just as the Brotherhood’s relationship with the rulers and their fellow government employees was constantly changing, so was the opinion of them held by the towns they were supposed to be guarding. As mentioned before, the hermandad was initially created as local militias in times of need. When they became a more powerful and more permanent institution, there were definite instances of abuses of power. There were the previously mentioned instances of the Holy Brotherhood silencing those who objected to Isabella’s reign. There were also reported instances of abuse by judges and archers, about whom the corregidores could do nothing. Guzmán de Alfarache (1599) is quoted in Lunenfeld’s book. He quotes: “God free us from the transgressions of the three Holies-Inquisition, Brotherhood, and crusade bull.” Complaints began appear requesting that the powers of the Holy Brotherhood be reigned in, and in 1485 police immunities were reduced and cases were brought up against the archers and judges.
The Holy Brotherhood was supported by the collection of taxes and by a special ability to collect wartime funding, called servicios which were granted by a papal bull as a crusading indulgence. Because the hermandad was usually backed by the crown and nobles, they were able to collect money from resistant towns with force.
 See also
- O'Callaghan, Joseph F. O. A History of Medieval Spain. (Ithaca, Cornell University Press, 1975), 448. ISBN 0-8014-0880-6
- Henry Kamen, Empire: how Spain became a world power, 1492-1763, 2002:7.
- Kamen 2002.
- Dutch Wikipedia: "Hermandad".
- [O’Callaghan, Joseph F. A History of Medieval Spain. Ithaca: Cornell University Press, 1975.]
- Lunenfeld, Marvin. The Council of the Santa Hermandad. Coral Gables: University of Miami Press, 1970.
- Lunenfeld, Marvin. Keepers of the City. Cambridge: Cambridge University Press,1987.