How Alexander the Great Secured His Borders Before Conquering the Persian Empire
When Philip II was assassinated in 336 BC, the Macedonian kingdom faced immediate collapse as vassal states revolted. Alexander the Great’s rapid, brutal pacification of the Balkans in 335 BC was not merely a reaction to chaos; it was a strategic necessity that cleared his path for the invasion of Persia.
Following the death of Philip II, the young king Alexander faced a cascade of rebellions from Thessaly to the Thracian tribes. His initial response was swift and diplomatic, securing his southern flank by maneuvering his cavalry to outflank the Thessalians, who surrendered without a fight. Recognized as Hegemon of the Greek forces at Corinth, Alexander quickly turned his attention north, where the Illyrians and Triballi threatened his stability. His northern campaign demonstrated a mastery of tactical innovation, such as his order for infantry to lie flat under shields to evade rolling carts at Mount Haemus.
The campaign was marked by both tactical brilliance and overwhelming force. At the River Lyginus, Alexander crushed a Triballian force, leaving 3,000 dead. When his ships failed to navigate the Danube, he improvised by using leather tents to construct rafts, ferrying 5,500 men across the river to intimidate the Getae. These victories were essential for establishing his reputation as a formidable monarch, ensuring that the northern tribes would not interfere while he focused on his primary objective: the Persian Empire.
The final test of his authority occurred when Thebes, emboldened by rumors of his death, declared independence. Alexander returned from the north and razed the city, selling its survivors into slavery. This decisive brutality brought mainland Greece back into submission, effectively ending the internal unrest. With his northern borders secure and the Greek city-states once again under his control, Alexander was finally free to launch the long-planned campaign against Persia that his father had envisioned.
