Pyrrhus of Epirus, King of Epirus; 319 BC - 272 BC

Being called the best general by Hannibal (alongside himself & Alexander the Great). Becoming king at 13 before being dethroned by the diadochi Cassander, Pyrrhus regained his throne during the 4th Diadochi war with the support of Ptolemy I Soter. This gave him valuable experience in the politics & military for his numerous exploits later. The list of enemies Pyrrhus had defeated is large including the major powers of Macedon, Rome, Sparta, Carthage let alone numerous other smaller powers. Yet for all his excellency on the battlefield, he proved to be unable to make full use of his victories. At the victory at the battle of Asculum, the term 'Pyrrhic victory' was coined meaning a victory so costly that it would tentamount to defeat, for while Pyrrhus did win the battle; he was unable to replenish his losses whilst the Romans could. https://www.livius.org/articles/person/pyrrhus-of-epirus/