During his own lifetime many considered him to be the most powerful ruler in the world yet fate rather than planning made him so.
He was born in the Netherlands during 1500, the eldest son of the Duke of Burgundy Philip I and Joanna of Spain. His father was also the heir to the Habsburg dynasty before drowning six years later. Charles became the Duke of Burgundy, and his mother went mad due to grief. Charles went on to become King of Spain in 1516.
Inheriting the Spanish throne meant that he became the ruler of a vast empire in Asia and the Americas. Closer to home it meant that he would spend most of his life fighting the French over disputed areas of Italy and his native Netherlands. The excellence of the Spanish infantry meant such wars were usually won. The death of his grandfather Maximilian led to his election as Holy Roman Emperor in 1519.
Charles found that the sheer size of his empire was more often a hindrance than of any great assistance. The unprecedented wealth generated in the Americas was frittered away in almost endless conflicts with the French as well as the Ottoman Turks. Things had got even more complicated with the onset of the Reformation whilst Charles was distracted by fighting in Italy.
Unlike the French, Charles never proved capable of defeating the Protestants, their survival being something he always regretted. Lutheranism survived because enough of the German princes were prepared to protect.
A burnt out Charles abdicated in 1556, leaving the Holy Roman Empire to his younger brother, and the rest of his realms to his son.
Lenman B (2004) The Chambers Dictionary of World History
Maland D (1986) Europe in the Sixteenth Century