Why was Philip II held hostage in Thebes as a young man?

Philip II was held hostage in Thebes as a result of Theban political and military activity in Macedonia during the 4th century BCE.1

Following the death of King Amyntas III in 370 BCE, Macedonia experienced a period of instability, which led Athens and Thebes to compete for influence over the region due to its valuable resources, such as timber. In the course of this power struggle, the Theban leader Pelopidas intervened in Macedonian affairs, and as an incidental result of these activities, the young Philip was taken to Thebes as a hostage.1

Historians have often noted that this period was significant for Philip’s development, as his exposure to the military methods of Thebes—which was then considered the leading military state in Greece—influenced his later army reforms and tactics.12