How was Spain formed from castile and aragon?

The Kingdom of Spain was formed through the dynastic union of the crowns of Castile and Aragon in 1479, when Ferdinand II of Aragon and Isabella I of Castile were married. This union laid the foundation for the modern Spanish state, although the two kingdoms retained their separate institutions and laws until the 18th century.

The process of unification was gradual and complex, involving military conquests, political negotiations, and dynastic marriages. In 1492, the conquest of the Emirate of Granada completed the Reconquista, the centuries-long effort by Christian kingdoms to reclaim the Iberian Peninsula from Muslim rule. This victory strengthened the position of the Spanish monarchy and facilitated further expansion.

In the early 16th century, the Spanish Empire reached its peak under the reign of Charles I (also known as Holy Roman Emperor Charles V). Charles inherited the thrones of Castile and Aragon from his grandparents, Ferdinand and Isabella, and expanded the Spanish territories through conquests in the Americas, Italy, and the Netherlands.

The reign of Philip II (1556-1598) marked the zenith of Spanish power and influence in Europe. Philip was the son of Charles I and inherited the vast Habsburg dominions. He ruled over a global empire that included territories in the Americas, Africa, Asia, and Europe.

However, Spain's power declined in the 17th century due to a combination of factors, including military defeats, economic problems, and political instability. The War of Spanish Succession (1702-1715) resulted in the loss of Spanish territories in Europe and the ascension of the Bourbon dynasty to the Spanish throne.

The Bourbon kings introduced a series of reforms aimed at centralizing power and modernizing the Spanish state. In the 18th century, the kingdoms of Castile and Aragon were finally unified under a single administrative system, creating the modern Spanish state.