Two years after the battle of Mantinea, Philip heard that his elder brother, the king, was dead, leaving only a young infant upon the throne. He went home at once and took the guardianship of the kingdom, gained some great victories over the wild neighbours of Macedon, to the north, and then made himself king, but without hurting his nephew, who grew up quietly at his court, and by-and-by married one of his daughters.  He had begun to train his troops to excellent discipline, perfecting what was called the Macedonian phalanx, a manner of arraying his forces which he had learned in part from Epaminondas.  The phalanx was a body of heavily-armed foot soldiers, each carrying a shield, and a spear twenty-four feet long.  When they advanced, they were taught to lock their shields together, so as to form a wall, and they stood in ranks, one behind the other, so that the front row had four spear points projecting before them.