Summary
"Concord Hymn" is a poem by Ralph Waldo Emerson written for the 1837 dedication of an obelisk monument in Concord, Massachusetts, commemorating the battles of Lexington and Concord, a series of battles and skirmishes on April 19, 1775 which sparked the American Revolutionary War. The poem was the origin of the phrase "shot heard round the world".
Source: Wikipedia (CC BY-SA).