John VI of Portugal

Born in Lisbon in 1767, John became heir after his older brother died of smallpox in 1788. He married Carlota Joaquina of Spain, who would spend decades conspiring against him. By 1799 his mother's mental illness forced him into a regency he held for seventeen years before formally taking the throne in 1816. Napoleon's invasion in 1807 drove him across the Atlantic to Brazil, where he spent over a decade laying institutional groundwork that historians now credit as the foundation of the modern Brazilian state. Forced back to Europe by liberal revolts, he watched his son Pedro declare Brazilian independence in 1822 and his other son Miguel lead a rebellion against him. He died in 1826, possibly by arsenic poisoning, having ruled through unbroken crisis - yet recent scholarship has reclaimed him as a tactician who held impossible forces in balance longer than anyone expected.