The Holy Roman Empire was maintained through an uneasy peace between political groups, with princes using their positions of power to control their vast and diverse territories. Charles's claims of universalism and cosmopolitanism in his empire were matched only by other great Roman rulers. Henry the Navigator sponsored early Portuguese voyages to Africa in the 15th century, changing European ambitions and society. Under Christian rule, Rome became the ultimate political expression of Christianity's universal message, with the Christian world order intended to endure as long as Earth itself. Las Casas wrote and advocated extensively against the injustices of colonialism from an intellectual rather than political perspective.