Isabel I la Cat ó lica (Spanish: April 22, 1451 – November 26, 1504) was the Queen of the Kingdom of Castile (reigned from 1474 to 1504).
In September 1468, Isabella was crowned crown prince by Enrique IV. On December 13, 1474, Isabella held a coronation ceremony in Segovia and declared herself Isabella I of the Kingdom of Castile. In 1475, the War of Succession to the Castile throne broke out. In 1479, the Treaty of Alcacovas was signed with Portugal, marking the end of the War of Succession. In 1482, war began with the Kingdom of Granada. In February 1492, the Kingdom of Granada was conquered. In the same year, Isabella I signed the Treaty of Santa Fe with Columbus, allocating funds to enable Columbus to embark on his voyages.
On November 26, 1504, Isabella I passed away due to illness at the age of 53.
Isabella I laid the foundation for political unity in Spain and worked hard to unify Spain ideologically, making it the center of the world, thus giving rise to Spain's hegemony. She was also a sponsor of Christopher Columbus crossing the Atlantic. Her influence extends beyond the Iberian Peninsula, causing significant changes on the European continent and the entire world.

Civilian life
In 1451, Isabella was born in the town of Pastoral in the Kingdom of Castile (now part of Spain). [3]
In 1454, Isabella's father Juan II passed away. At that time, Isabella was only 3 years old and her younger brother Alfonso was only 8 months old. In the same year, Isabella's half brother Enrique IV succeeded to the throne and drove his stepmother, who had always been at odds with him, along with the young Isabella and Alfonso, out of the palace. Isabella followed her mother to the countryside and settled in the Alevano Castle, beginning her life as nothing more than a commoner. Not only that, but also her mother, who suffered a great decline in life, carried humiliation and poverty, gradually became mentally unstable and eventually became a madman. Isabella had to shoulder the responsibility of taking care of her younger brother and mother, during which time she became a devout Catholic. [2]
Becoming a Crown Prince
After Enrik IV succeeded to the throne, he remained childless until 1462, when he was 37 years old, when he had a daughter named Juana. Juana was then confirmed as the heir to the throne, but there were rumors that Juana was the illegitimate daughter of the queen and knight Belante. Enrique IV repeatedly emphasized that this was a rumor, insisting that Juana was definitely his biological daughter, but the nobles still demanded the cancellation of her inheritance rights, and even demanded that Enrique IV himself abdicate. The conflict between Enrique IV and the nobles quickly intensified. [4]
On September 28, 1464, opposition nobles issued a statement demanding that Enrique IV abdicate and began using force to blackmail. Enrique IV had no choice but to announce the abolition of Juana's inheritance rights on November 30th and establish his half brother Alfonso as the crown prince. However, in June 1465, opposition nobles still convened a meeting in Avila to announce the deposing of Enrique IV and the establishment of Alfonso as the King of Castile, leading to a civil war. At that time, Isabella was arrested by Enrique IV and imprisoned in the palace. In 1468, Isabella fled the palace and returned to her brother Alfonso's camp. But soon after on July 5th, Alfonso died suddenly. At this point, the rebellious nobles planned to replace her with Isabella. But Isabella was stubborn and stated that as long as her brother was alive, no one had the right to usurp the throne.

In September 1468, the opposition reached the Toros de Gissando Agreement with Enrique IV, in which Isabella recognized Enrique IV as king and Enrique IV appointed Isabella as crown prince, emphasizing that Isabella's marriage must be personally decided and arranged by him. Enrique IV wanted to marry Isabella to King Alfonso V of Portugal, but Isabella fell in love with Prince Fernando of Aragon. Enrique IV was very angry when he found out, and he immediately emphasized that as the crown prince, Isabella's marriage must be arranged by him personally, otherwise her inheritance rights will be revoked. But Isabella weighed the pros and cons and in the autumn of 1468, secretly crossed the border to negotiate with the Crown Prince Fernando of the Kingdom of Aragon. [4] [6]
On January 7, 1469, Isabella signed a marriage contract with Fernando. Fernando promised to abide by the laws of the Kingdom of Castile in his engagement, never betray his wife, and negotiated with her to determine candidates for military and civilian positions. In August, Isabella arrived in Valladolid. [5] On October 19th, Isabella and Fernando held a grand wedding at the Juan Bivero Palace in Valladolid. [6]
On October 25, 1470, Enrique IV, who was very angry about Isabella's marriage to Fernando, abolished Isabella's inheritance rights, declared Joanna his biological daughter, restored her to the throne, and demanded that Isabella marry the brother of King Louis XI of France. Isabella, on the other hand, issued a proclamation to the whole country condemning Enrique IV for betraying the Toros de Gissando Agreement and declaring that he would never surrender. The nobles immediately divided into two factions, and the domestic situation in the Kingdom of Castile was tense. This tense situation lasted until 1473 when Enrique IV came to Segovia to negotiate with Isabella, but he did not declare the restoration of Isabella's inheritance rights.

Strong Ascension
Main entry: War of Castile Succession
On December 11, 1474, Enrique IV passed away, and on that day Fernando happened to return to Aragon to quell the rebellion. Isabella made a decisive decision upon receiving the news and held her coronation ceremony on December 13th in Segovia. Announcing herself as Isabella I of the Kingdom of Castile, and her husband Fernando as co ruler, known as Fernando V of the Kingdom of Castile. [4] The coronation ceremony caused dissatisfaction among the stubborn aristocrats who insisted on their feudal privileges. They colluded with King Alfonso V of Portugal to marry Princess Juana and elevate Juana to the throne, competing with Isabella I for the rule of Castile. [7]
Winning the Civil War
In January 1475, the Civil War broke out in Castile, and Isabella I immediately granted her husband Fernando great power. [5] In May, Afonso V led more than 20000 troops across the Portuguese border and occupied Palenia. Isabella I formed a 40000 strong army to confront it. [7] In September, France formed an alliance with Portugal. In the first few months, the Portuguese army quickly occupied a large part of the neighboring areas of Estremadura and Galicia, and subsequently occupied Toro and Samora. In addition, places such as Burgos are controlled by the opposition; The French army began to invade the northern border.
In March 1476, the Battle of Toro broke out, with Fernando winning and the morale of Portuguese soldiers greatly weakened. Subsequently, both sides engaged in a diplomatic war to woo France, and Aragon announced the abandonment of its demand for the jurisdiction of Roussellon, which had serious disputes with France. As a result, the French army came to a halt. Subsequently, Isabella I moved the palace to the ancient capital Toledo, held a kingdom council, and then went to the south to rectify the feudal relationship in those areas. The northern war was fully commanded by her husband.

In 1477, Isabella I's rule over the south was consolidated. [4] In the same year, religious courts were established nationwide and the highest religious court was established. [8]
In 1478, Isabella I and Fernando jointly signed a formal peace agreement with King Louis XI, completely eliminating military threats from the north. [4]
In 1479, Fernando annihilated the main military force of the opposition aristocracy in Castile through the Battle of Albrella. In the same year, he inherited the throne of Aragon from his deceased father and was known as Fernando II. He declared Isabella I his co ruler in Aragon, just like he did in Castile. Portugal saw that the situation had passed and had to sit back at the negotiating table. On September 4th of that year, both sides signed the Alcakovas Treaty, declaring the end of the war. The treaty stipulated the termination of the engagement between Alfonso V and Juana, and the Portuguese army withdrew from Castile. Afterwards, the Kingdom of Castile and the Kingdom of Aragon were in a state of union, and after the union, each country still had its own parliament, government, law, army, tax system, and currency. However, in reality, all decisions of the two countries were jointly made by Isabella I and Fernando II. [3-4]
Recapture lost territory
On the evening of December 27, 1481, King Abu Hassan of the Kingdom of Granada raided Saara in the Kingdom of Castile and killed all its residents. [9]
In February 1482, Isabella I called on knights holding royal land and allowances from all over the country to participate in the war of the recapture movement. Infantry and light cavalry from northern Castile and some highland towns, as well as some mercenaries from Aragon and Switzerland, gathered in Medina. Isabella used her jewelry as collateral to borrow money from the cathedral in Valencia. [9] During the war, Isabella I sent envoys to contact various Western European countries to gain support, and at the same time, adopted a strategy of division to disintegrate the enemy camp, which was repeatedly effective. She also frequently visited the front line to boost morale.
In 1485, Isabella I established the first military hospital in Europe, Queen's Hospital, to strengthen military logistics work. [7]
On January 20, 1486, Isabella I received Christopher Columbus in Alcala and listened to his plans for a long voyage. [5-6]
On January 2, 1492, the last monarch of the Kingdom of Granada, Mohammad XII, signed a surrender agreement with Abdir. On January 3rd, the city was officially opened and surrendered. On March 31st, Isabella I issued the Law on the Conversion or Expulsion of Jews. [5] In the same year, Isabella I once again received Columbus and ordered the formation of a special committee to discuss Columbus's plans. On April 17th, Isabella I disregarded the opposition of Fernando II and some nobles and signed the Treaty of Santa Fe with Columbus, allocating funds to enable Columbus to embark on his voyage.

On December 19, 1496, Pope Alexander VI conferred the titles of Catholic kings Isabella I and Fernando II. [5]
On February 12, 1502, Isabella I began expelling Muslims who had not changed their faith in Granada. [5]
Death due to illness
In the summer of 1504, Isabella I and Fernando II both fell ill. On October 12th, Isabella I made a will. On November 26th, Isabella I passed away at the age of 53.

politics
Parliamentary reform and establishment of a cabinet
Isabella devoted her entire life to establishing an absolute monarchy. In 1480, Isabella convened a parliament in Toledo to carry out comprehensive parliamentary reforms. The power of the reformed parliament has been greatly restricted, and its discussion is limited to proposals proposed by the royal family, no longer possessing legislative and financial powers, only retaining the following rights: 1. to announce and notify the heir to the throne; 2. Maintain contact with the local government, such as allocating funds for local construction; 3. Allow representatives to submit petitions on local affairs in parliament. The royal family will provide some compensation to representatives in the form of wages and gifts. Parliament is only convened when the king deems it necessary. Through parliamentary reform, Isabella weakened the power of parliament, strengthened royal power, and consolidated the authority of the royal family.
In addition, Isabella also established her own cabinet, which is mainly divided into five departments. The first department is dedicated to handling affairs between the rulers of the Kingdom of Castile and other countries and the Pope, and its decisions are binding. Its members mainly include important figures, popular royal advisors, and royal secretaries, and also include the two kings when approval is needed. The second department is dedicated to judicial matters. Both departments are within the Royal Parliament. The third department is composed of knights and lawyers, specifically responsible for business dealings with Aragon, Catalonia, Sicily, and Valencia. The fourth department is composed of members of the Holy Brotherhood. The last department is composed of Contadores, the mayor, and officials in charge of managing finances and royal property books. These people are responsible for evaluating the country's annual income, arranging next year's cultivation, and also recording the country's expenditures. These five departments are all controlled by Isabella's confidants. In the past, nobility held an important position in parliament, but this era has passed. Isabella trusted her cabinet more, and the cabinet completely replaced the parliament. Through parliamentary reform and the establishment of a cabinet, Isabella gained complete control of the parliament, which became a tool for Isabella to consolidate her rule, strengthen centralization, and lay the foundation for the later conscription and taxation of the recapture movement.

economic
Reclaim Royal Territory and Rent
In 1480, Isabella announced the recovery of the royal territories and rent that had been granted to Enrique and Alfonso during their reigns, thereby increasing the country's fiscal revenue. For some nobles and clergy who did not support Isabella at the time, she promised to guarantee their property and status. The nobles only returned a portion of the royal rent they had received since 1464. As for the remaining part, the royal family recognized it as legal. The nobles acknowledge that the authority of the royal family is higher than themselves and can make laws; On the contrary, the royal family ensured the economy and status of the nobility.
Monetary reform
Isabella I and Fernando II also carried out currency reforms. They implement the gold standard and strictly prohibit the export of gold, silver, and currency. In addition, they also devalued their currency, which is beneficial for increasing the value of gold and thus for Castile, which started storing gold early on. These fiscal measures greatly increased Castile's annual revenue, which more than doubled from 1477 to 1482. [9]
Funding Columbus
In 1492, after completing the campaign to recover lost territories, Spain's financial resources were almost depleted and it urgently needed to obtain supplies from overseas. So Isabella I disregarded the opposition of Fernando II and some nobles and signed an agreement with Columbus, allocating funds to enable Columbus to embark on his voyage. Over the next 10 years, Isabella I sponsored Columbus on four trips in search of the New World. These four voyages opened up vast overseas territories for Spain in the following century, and wealth flowed continuously into Spain. According to statistics, from 1502 to 1660, Spain received 18600 tons of silver and 200 tons of gold from the Americas. By the end of the 16th century, 83% of the world's total gold and silver production was occupied by Spain. Spain thus dominated the world, and the route of European overseas trade shifted from the Mediterranean to the Atlantic coast.

diplomacy
And the Kingdom of Granada
Isabella I and Emil of the Kingdom of Granada signed ceasefire agreements in 1475 and 1476, respectively. The agreement stipulates that both parties shall not engage in war for at least five years. However, during this period, some small-scale conflicts at the border occurred occasionally. In 1481, the Kingdom of Granada attacked the Kingdom of Castile. In 1482, Isabella I launched a movement to reclaim lost territories and conquered the Kingdom of Granada in 1492. [9]
With Portugal
In May 1475, Alfonso V of Portugal intervened in the War of Succession to the Castile throne, leading his army to attack Castile and occupying some of its territory. [7] In 1479, Portugal signed the Treaty of Alcacovas with Castile, declaring the end of the war and the withdrawal of Portuguese troops from Castile. [3]
With France
In September 1475, France formed an alliance with Portugal and invaded the northern border of Castile. In March 1476, Aragon announced the abandonment of its claim to the jurisdiction of Roussellon, which had serious disputes with France, and reconciled with France. [4] In 1495, France occupied Naples. In the same year, Spain formed a "Holy Alliance" against France with the Holy See, Venice, Milan, and the Holy Roman Empire, and the French army retreated. In 1501, a treaty was made with Spain to divide Naples, and a war broke out due to uneven distribution of spoils. In December 1503, the Western army defeated the French army in the Battle of the Galliano River and obtained Naples. [13]
military affairs
Military construction
Isabella I had her own vassals, known as the "royal vassals.". These vassals accept the land or cash bestowed by Isabella in return for directly serving the royal family. These vassals were a reliable source for the king to summon additional troops and played a significant role in the process of recapturing lost territory. [12]
Foreign War
Main entry: Movement to reclaim lost territory
Due to the failure of the Moors and Castile in Granada to abide by the ceasefire agreement, Isabella I decided to use force to drive the Moors away. This war lasted for 10 years (1482-1492). During the war, the army of Fernando II, the husband of Isabella I, always charged ahead of the army led by Isabella. Isabella, on the other hand, acted more like a military and financial officer, providing logistical support for all soldiers. Isabella also went to various military camps to comfort soldiers in tents, established battlefield hospitals and frontline emergency tent hospitals, which are also affectionately known as Queen's Hospital. [14] In 1492, after besieging the capital of the Kingdom of Granada for over a year, the last monarch of the Kingdom of Granada, Mohammed XII (known as "Boabdir" in Spain), opened his city and surrendered. The fall of Granada declared the downfall of the last Arab dynasty, and the movement to reclaim lost territories ended in victory.

religion
Religious reform
After succeeding to the throne, Isabella decided to purify the Spanish church and strengthen the royal control over the church. Isabella I and Fernando II repeatedly emphasized that the king is the representative of Jesus Christ in the world and has the right to intervene in religious affairs. The more important reform content is the redefinition of dioceses. The bishops of these dioceses must be knowledgeable and loyal Castilians to Isabella. They must have a middle-class background and cannot be powerful nobles or foreigners. So she fought against the church in a way that had the power to appoint bishops, thus gaining control of the church. In 1479, Pope Sixtus IV appointed his cardinal as the bishop of Castile Kunca. Upon hearing this, Isabella immediately sent an envoy to convey her will to the Pope: the Pope's order to appoint foreigners as bishops of Castile must be revoked, and future appointments of bishops must be approved by the royal family. In 1480, the prohibition of foreigners from serving as bishops was established in parliament. [12] In 1482, Isabella signed an agreement with the Pope. A confidant of Isabella became the bishop of Kunca. As a consolation, the Pope's nephew received Salamanca and his son became the bishop of Cartagena. The bishops are all living under Isabella's surveillance. Isabella achieved a partial victory. Throughout Isabella's life, although she was a devout Catholic, she never allowed Catholic orthodoxy to interfere with her Spanish nationalism. In order to ensure that the Spanish Catholic Church was under the control of the Spanish monarchy rather than the Pope, she and Ferdinand worked hard and achieved success. This is one of the reasons why the religious reform of the 16th century did not make any progress in Spain. [3]
Establish a religious tribunal
In order to establish a religious unity in Spain, Isabella I and Fernando II established a new form of religious court in Spain, which was different from other parts of Europe. It was an inevitable result of Isabella and Fernando's strengthening of royal power and a political weapon. The initial purpose of establishing a religious tribunal was to maintain the purity of Spanish Christianity, mainly targeting Jews. On November 1, 1478, Pope Sixtus IV allowed Isabella to select 2-3 clergy from all clergy to serve as interrogators, granting her the legitimacy to examine the authenticity of Jewish converts or newly converted Christians. The Inquisition Office was established in Castile. In 1482 and 1483, religious courts were established in the cities of Cordoba, Hahn, and Reil. [12] The trial court is composed of judges, juries, prosecutors, and police officers. It does not give the defendants an opportunity to defend themselves, they cannot refute the charges imposed on them, they do not know all the evidence against them, and they cannot even know the names of the accusers. The defendants only have the right to be tortured until they admit the charges against them. According to a conservative estimate, in the first 20 years, at least 2000 people in Spain died at the stake, and several times more people received lighter punishments than those at stake.

Another important reason for establishing religious courts to expel Jews is to plunder their property. Jewish converts gained great financial and political status in Spanish society, occupying important positions in both the country and the church, which older Christians could not tolerate. The decision-maker behind the Spanish Inquisition is the King of Spain, while the Pope is only in a secondary and controversial position. The religious court confiscated the property of Jewish converts while persecuting them, and a large part of this property was directly handed over to the royal family. The property obtained by the royal family provided economic security for the recovery movement. The establishment of religious courts caused great harm to Jews, and a large portion of merchants and artisans in Spain were displaced, resulting in a serious economic blow to Spain. However, it cannot be denied that the religious tribunal gave the Christians on the peninsula a unified sense of national identity, and the unity in the spiritual realm enhanced Isabella's appeal in the process of reclaiming lost territories, becoming an important reason for Isabella's successful leadership of the Christian army in reclaiming lost territories. [12]
This series of measures greatly strengthened the power of authoritarian monarchy, while also strengthening the orthodox status of Catholicism and the role of the Church as a stubborn pillar of maintaining feudal monarchy. As a result, Spain developed into a centralized monarchy.

Italian humanist Petro Mattier de Angleriria: The pen fell from my hand, power disappeared in sadness, and the world lost its most precious treasure. She has long guided Spain towards prosperity. Her fall should not only be deeply mourned by the Spaniards, but also by all Christian countries, because she is a mirror of virtue, a guardian deity of the innocent, and a hater of evil. I doubt which of those female heroes from ancient times and present can surpass this unparalleled woman in value! [15]
James A. Michener's Iberia: She was a giant of that era, a woman who supported Columbus in discovering the New World. [16]
American scholar Mike Hart's "Ranking of 100 People Who Influenced the Process of Human History": It is often natural to compare Isabella with Queen Elizabeth I of England. Elizabeth's abilities are comparable to those of Isabella, but her humane and tolerant policies have earned her more respect. But she is not as daring to innovate as Isabella, and there is no policy that can have as profound an impact as Isabella's trial system. Although Isabella's policies were extremely cruel, the influence of only a few monarchs in history can be compared to them. [6]
Beijing Morning News: ① Isabella is the Queen of Spain, known as a talented and energetic ruler, and her sponsorship of Columbus's expedition has become an important political card for her. The series of decisions made by this queen had a profound and significant impact on the later development of Spain and Latin America Queen Isabella is one of the important women in European history. She laid the foundation for modern Europe and America, and her achievements in this area exceeded those of anyone at the time.