History & Religion

Queen Isabella I

Isabella I reigned as Queen of Castile from 1474 until her death. Her marriage to Ferdinand II in 1469 became the basis for the de facto unification of Spain.

Queen Isabella I of Castile (1451 – 1504) was an influential monarch who helped to unite the different regions of Spain and make Spain a leading power in Europe and the Americas.

Queen Isabella was a strict Catholic and, amongst contemporaries, was noted for her ‘virtue and fear of God’.

She was an effective monarch in bringing greater law and order to the country and had areputation for promoting justice rather than mercy.

With her husband King Ferdinand, she set up the Spanish Inquisition, to investigate heretical religious practises.

  • Born: 22 April 1451, Madrigal de las Altas Torres, Spain
  • Died: 26 November 1504, Medina del Campo, Spain
  • Full name: Isabella I reigned as Queen of Castile

About Isabella I reigned as Queen of Castile

Isabella was born in 1451 in Madrigal in the Kingdom of Castile (part of Spain). Her half-brother Henry IV was King of Castile, and he wished Isabella to marry the King of Portugal in a marriage of convenience.

Henry IV planned to make Isabella his successor. However, Isabella disliked her half-brother, and at the age of 18 in 1469 she married Prince Ferdinand – the heir to the Kingdom of Aragon – a neighbouring kingdom in Spain.

As a result, Henry IV disinherited his half-sister in favour of his own daughter Juana.


In 1474, Henry IV died, and this led to conflict between supporters of Isabella and Juana for the throne of Castile.

Initially, Isabella had only a few supporters amongst the powerful of Castille, but in December 1474, she had the confidence to have herself crowned as queen, usurping the former king’s daughter.

It led to several years of conflict between the rival factions for the throne – during this period she showed her strength and resolve to cement her power.

For example, in 1476, a rebellion broke out in Segovia. With her husband away, Isabella ignored her male advisers and took it upon herself to ride out to meet the rebels.

She successfully negotiated with them to drop their grievances, and she was successful in bringing it to an end without bloodshed.

At the time, it was unusual for women to take such an active approach to matters of the state. She was a pioneer for powerful and influential queens who would follow in the next few centuries.


In 1474 – her husband Ferdinand became King of Aragon. They agreed to rule together – becoming an effective couple who would discuss decisions and actions.

Their joint rule led to increased centralisation and effective unification of the Spanish kingdoms. In 1479, she completed her triumph in securing the throne of Castile becoming undisputed queen.

During her reign, she also oversaw a change in medieval warfare – because she vastly increased the numbers of cannon and this made castles much more vulnerable to attack. This had a big influence on the nature of warfare.


When Isabella came to the throne, the kingdom of Castille suffered serious problems due to misrule by her brother Henry IV.

In particular, he had been profligate in spending and ignored issues of law and order. When Isabella came to the throne, there was no reliable system for bringing criminals to justice.

She successfully financed a justice system and police force through a new tax. She was also successful in improving the nation’s finances by making better use of Royal lands, which has been sold cheaply by her brother.

She also instituted a Royal monopoly over the money supply and this helped to increase confidence in the nation’s coins and finances.