Julius Caesar Crosses the Rubicon
By 49 BCE the Roman Republic was rotting from within — its politics gridlocked, its generals commanding armies loyal to them rather than the state. Ordered by the Senate to disband his legions, Julius Caesar instead led them across the Rubicon river into Italy, an act of war against his own country, and won. His crossing is the moment the Republic effectively died, though it took his heir to formalize it — the recurring pattern of a broken system yielding to the strongman who promises to fix it.
Prolonged chaos creates demand for order; a single figure concentrates power by promising to supply it.