The critical event that marked the turning point in the North American Revolutionary War was the Battle of Saratoga in 1777. This decisive American victory is often considered the war's turning point because it bolstered American morale and convinced France to ally with the colonies. The influx of French military support was crucial for the American cause, providing resources and a crucial naval presence against the British forces. The victory at Saratoga ultimately changed the dynamics of the war and paved the way for eventual independence from British rule.