The significant event that started the French Revolution in 1789 was the convening of the Estates-General in May of that year, primarily due to France's fiscal crisis and widespread discontent among the Third Estate (commoners). Tensions escalated, leading to the storming of the Bastille on July 14, 1789, which symbolized the uprising against the monarchy and the fight for liberty and equality. This revolution fundamentally transformed French society and government, ultimately leading to the establishment of a republic and influencing revolutionary movements worldwide, reshaping ideas about governance and rights.