The writings of john L. O Sullivan showed the power of?

John L. O'Sullivan's writings exemplified the power of Manifest Destiny, the belief that the United States was destined to expand its territory across North America. His phrase "Manifest Destiny" articulated a sense of mission and entitlement to spread democracy and civilization, reflecting the prevailing attitudes of the time. O'Sullivan's ideas influenced public opinion and policy, underpinning the justification for westward expansion and the annexation of lands. Ultimately, his work highlighted the intertwining of national identity and expansionist ideology in 19th-century America.