The Shot Heard 'Round the World

"The shot heard round the world" is a phrase which refers to an event that precipitates or completes a major conflict or contest, most commonly the first gunfire at the beginning of a war. The phrase originated in a poem which describes the 1775 Battles of Lexington and Concord which opened the American Revolutionary War, but it has since been used to refer to other events, such as the assassination of Archduke Franz Ferdinand of Austria in 1914.

The phrase comes from the opening stanza of Ralph Waldo Emerson's "Concord Hymn" (1837) and refers to the first shot of the American Revolutionary War. According to Emerson's poem, this pivotal shot occurred at the North Bridge in Concord, Massachusetts, where the first British soldiers fell in the battles of Lexington and Concord.

Historically, no single shot can be cited as the first shot of the battle or the war. Shots were fired earlier at Lexington, where eight Americans were killed and a British soldier was slightly wounded, but accounts of that event are confused and contradictory, and it has been characterized as a massacre rather than a battle. The North Bridge skirmish did see the first shots by Americans acting under orders, the first organized volley by Americans, the first British fatalities, and the first British retreat.

The question of the point of origin of the Revolutionary War has been debated between Lexington and Concord and their partisans since at least 1824, when the Marquis de Lafayette visited the towns. He was welcomed to Lexington hearing it described as the "birthplace of American liberty", but he was then informed in Concord that the "first forcible resistance" was made there. President Grant considered not attending the 1875 centennial celebrations in the area to evade the issue. In 1894, Lexington petitioned the state legislature to proclaim April 19 as "Lexington Day", to which Concord objected; the current name for the holiday is Patriots' Day.

...
Wikipedia