The phrase "shots heard 'round the world" refers to the first military engagements of the American Revolutionary War, specifically the battles of Lexington and Concord, which took place on April 19, 1775. These skirmishes marked the start of armed conflict between Great Britain and the American colonies. The phrase emphasizes the global significance of the events, as they signified the colonies' determination to fight for independence. It reflects how the struggle for liberty would resonate beyond the colonies, inspiring other nations and movements toward self-determination and democracy.