 In 354 or 353 BCE, the Thessalians, having been defeated by the Phocians, requested that Philip become archon of Thessaly, to which Philip assented, drawing Macedon into the Sacred War.In 352 BC, Philip's erstwhile ally, the Chalkidian League (led by Olynthos), alarmed by Philip's growing power, sought to ally themselves with Athens, in clear breach of their alliance with Philip.In response, Philip attacked Chalkidiki in 349 BC, and by 348 BC, had completely destroyed the Chalkidian League, razing Olynthos in the process.