Henry was born in Havel, Margraviate of Brandenburg, Holy Roman Empire in 1260, the son of Margrave John I of Brandenburg. He belonged to the House of Ascania, which ruled over Saxony and Brandenburg, and his family possessed a large amount of lands in northeastern Germany. Due to his influence in politics, he was elected as Holy Roman Emperor by the Imperial Diet following the death of Henry VII of Germany from the plague. Henry VIII's reign was extremely short, as he was already ill with the dreaded plague. After just three days, Emperor Henry VIII died of the disease, and William d'Avesnes of Holland was elected the new emperor.