John L. O'Sullivan

John L. O'Sullivan was a 19th-century American journalist and editor, best known for coining the phrase 'Manifest Destiny,' which encapsulated the belief that the United States was destined to expand across the North American continent. His writings in the 'New York Morning News' advocated for the annexation of territories and reflected the era's expansionist sentiments. O'Sullivan's ideas played a significant role in shaping American political discourse during a time of significant territorial growth and conflict.