Why is the Battle of Lexington and Concord known as the "shot heard 'round the world?"

The phrase comes from the opening stanza of Ralph Waldo Emerson's "Concord Hymn" (1837) and refers to the first shot of the American Revolution at the Old North Bridge in Concord, Massachusetts, where the first British soldiers fell in the battles of Lexington and Concord on April 19, 1775.

christopher columbus (1492–1504)

answer; i believe the two groups were irish immigrants and chinese immigrants;