McEachin served in the United States Army before, and then during, the Korean War. Serving in King Company, 9th Infantry Regiment (United States), 2nd Infantry Division, he was wounded (nearly fatally) in an ambush and nearly left for dead. McEachin was one of only two soldiers to survive the ambush. He was awarded both the Purple Heart and Silver Star in 2005 by California Congressman David Dreier after McEachin participated in a Veterans History Project interview given by Dreier's office and in which they discovered McEachin had no copies of his own military records. Dreier's office quickly traced the records and notified McEachin of the Silver Star commendation and awarding him all seven of his medals of valor shortly thereafter, fifty years after his service.
In the 1990s, he semi-retired from acting to pursue a writing career. His first work was a military history of the court-martial of 63 black American soldiers during the First World War, titled Farewell to the Mockingbirds (1995), which won the 1998 Benjamin Franklin Award. His next works, mainly fiction novels, included The Heroin Factor (1999), Say Goodnight to the Boys in Blue (2000), The Great Canis Lupus (2001), and Tell me a Tale: A Novel of the Old South (2003). He published Pebbles in the Roadway in (2003), a collection of short stories and essays which he describes as "a philosophical view of America and Americans". In 2005, McEachin produced the award-winning audio book Voices: A Tribute to the American Veteran.