A Wisconsin native and namesake son of a noted medieval historian, Gaines Post, Jr., was educated at Cornell, Oxford (Rhodes scholar) and Stanford. He taught modern European history at the University of Texas, Austin, and at Claremont McKenna College, where he also served as dean of faculty. His two major scholarly books examine foreign policy and military planning in Germany and Great Britain between the World Wars. His two memoirs describe coming of age and military service in the Cold War 1950s, and driving across much of America solo in his 1966 VW Bug in 2002, at age 65. He has canoed in the North Woods, worked cattle on ranches in Texas and Wyoming, and backpacked in the Rockies and Sierra Nevada. He helped raise two children before losing his wife, Jean, to muscular dystrophy. He lives in Santa Rosa, California, at the northern end of the Sonoma Valley.