John T. O'Sullivan

John T. O'Sullivan was a 19th-century American journalist and editor best known for coining the term "Manifest Destiny," which described the belief that the United States was destined to expand across North America. This idea played a significant role in shaping American policies and attitudes toward westward expansion, justifying territorial acquisitions such as Texas and California. O'Sullivan argued that this expansion was not only inevitable but also a moral right, reflecting the belief in American exceptionalism and the spread of democracy. His ideas significantly influenced public opinion and policy during the 1840s.