The Illyrian king Bardylis pioneered many of the techniques that Philip and Alexander would use to such devastating effect, such as the tactics of combined infantry and cavalry. Philip witnessed the evolution of these tactics first-hand during his ten-year sojourn as a political hostage in Bardylis' household.
In 393 BC, the Illyrians forced Philip II's father, Amyntas III, to abandon his kingdom at least once. After several resounding defeats, Bardylis commanded Amyntas to surrender his son Philip to him as a hostage. As a result, the young prince would remain in Illyrian custody for ten years, training alongside the other members of Bardylis' household, until he was transferred from Illyria to Thebes, again as a hostage for Macedonian good behaviour. These ten years in Illyria occurred during the crucial period when Bardylis was consolidating his control over the disparate clans of Illyria and pushing against his Greek neighbours, the Molossians, the kingdom of Alexander the Great's maternal grandfather. Such a sojourn would have profoundly affected Philip's thoughts about military development and given him many practical examples of how to unite and maintain a multi-ethnic kingdom as well as how a combination of mobile infantry and cavalry might be deployed against both Greek hoplite armies and the light cavalry
