Charles V was a Holy Roman Emperor from 1500-1558 who inherited vast territories throughout Europe and sought to reunite the continent under his rule. Through inheritance from his grandfathers, Charles V came to control central and eastern Europe, Spain, Castile and Aragon. During his reign, he successfully reunited all of Europe for the first time under a single ruler, though rumors spread that he aimed to conquer the entire world. Despite lacking common legal or administrative systems across his empire, Charles V was still able to expand his territories through large, well-trained standing armies.