Lexington and Concord were the sites of the first fighting in the Revolutionary War. During his famous midnight ride, Paul Revere warned Minutemen in Lexington about the approach of the British. Minutemen were citizens of Massachusetts who had organized themselves into a militia. They were called Minutemen because they were supposed to be ready to fight "at a minute's notice." Captain John Parker was one of their commanders, and some people believe that he said to the Minutemen: "don't fire unless fired upon, but if they mean to have a war, let it begin here." Although it is unlikely that he actually said this, since no one heard about the quote until 1858, Parker did order the militia to disperse and not to fire when the British suddenly approached. No one knows who fired the first shot, but, in "Concord Hymn," Ralph Waldo Emerson described it as "the shot heard round the world" because of the importance the Revolutionary War and the United States would have in world history.