<P> The term is derived from the Thin Red Line, a formation of the 93rd Highland Regiment of Foot of the British Army at the Battle of Balaclava in 1854, in which the Highlanders stood their ground against a Russian cavalry charge . This action was widely publicized by the press and became one of the most famous of the Crimean War . </P> <P> The first known use of the phrase "thin blue line" is from a 1911 poem by Nels Dickmann Anderson, titled "The Thin Blue Line ." In the poem, the phrase is used to refer to the United States Army, alluding to the Thin Red Line, and to the fact that US Army soldiers wore blue uniforms from the eighteenth century through the nineteenth century . </P> <P> It is unknown when the term was first used to refer to police . In the 1950's, LAPD Chief Bill Parker used the phrase in the department - produced television show of the same name . Parker coined the term thin blue line to further reinforce the role of the LAPD . As Parker explained, the thin blue line, representing the LAPD, was the barrier between law and order and social and civil anarchy . The phrase is also documented in a 1965 pamphlet by the Massachusetts government, referring to its state police force, and in even earlier police reports of the NYPD . By the early 1970's, the term had spread to police departments across the United States . </P> <P> Use of the term became especially widespread following the release of Errol Morris' 1988 documentary film The Thin Blue Line, about the murder of a Dallas Police officer Robert W Wood . Judge Don Metcalfe, who presided over the trial of Randall Adams, states in the film that prosecutor "Doug Mulder's final argument was one I'd never heard before: about the' thin blue line' of police that separate the public from anarchy ." The judge admitted to being deeply moved by the prosecutor's words, though the trial resulted in a wrongful conviction and death sentence . </P>

What does a black us flag with a blue stripe mean