The riches of New Spain helped make the sixteenth century the Golden Age of Spain. After Queen Isabella and King Ferdinand died, their sixteen-year-old grandson became King Charles I of Spain in 1516. Three years later, just as Cortés ventured into Mexico, King Charles became Holy Roman Emperor Charles V. His empire encompassed more territory than that of any other European monarch. He used the wealth of New Spain to promote his interests in sixteenth-century Europe. He also sought to defend orthodox Christianity from the insurgent heresy of the Protestant Reformation. The power of the Spanish monarchy spread the message throughout sixteenth-century Europe that a New World empire could bankroll Old World ambitions.