Louis I of Hungary

Louis inherited Hungary in 1342 at full age with a rich treasury and a mother whose piety shaped his reign. When his brother Andrew was murdered in Naples in 1345, he blamed Queen Joanna I and launched two brutal invasions between 1347 and 1350, adopting Neapolitan titles the pope never recognized; his mercenaries' atrocities made Southern Italy despise him, and he pulled out in 1351. He spent the 1350s reclaiming frontiers against Lithuanians, Serbs, Tatars, and the Golden Horde, bending Venice in 1358 and asserting nominal control over Balkan rulers who resented his Catholic conversion drives. Poland fell to him in 1370 after his uncle Casimir died sonless, but he stayed unpopular there and spent his last years - skin disease eating at him - deepening his faith and backing Charles of Durazzo's seizure of Naples. He died in 1382 with no sons, leaving two daughters and a legend of three-sea dominion that Hungarian chronicles repeated for centuries.