Isabella I of Castile and Ferdinand V of Aragon married on this day in 1469, marking the beginning of the unification of Spain. As the monarchs of two of three Catholic kingdoms in Iberia (Portugal being the third), their marriage saw the two kingdoms united, as their daughter, Joanna, succeeded Isabella first and her father upon his death as well. When Joanna died in 1555, her son Charles V became King of Spain, as well as Holy Roman Emperor. The marriage of Isabella and Ferdinand also marked the beginning of the Reconquista, and by 1492, the entire Iberian peninsula was Catholic, with Granada being the last Muslim nation to fall. The joint reign of Isabella and Ferdinand was also responsible for Christopher Columbus’s expedition to the Americas, and Spain’s beginning as a colonial power, and transformation into the richest and most powerful nation in Europe. Isabella died first in 1504, while Ferdinand died in 1516. Their daughter, Catherine, later married Henry VIII of England, who was the mother of Mary I of England.