He wrote mostly SF but also historical fiction (mainly around norse sagas) and fantasy (also often tied to sagas or classical history).
Am rereading some of his fantasy. currently on A Midsummer Tempest. Recently read Three Hearts, Three Lions and The Broken Sword. has been about 6 years since I last read those titles.
Anyone else like this author? One of my very favorites - van rijn, flandry, hanno, time patrol, and so many stand-alone novels.
It is a bit depressing to see highly regarded, prolific sf authors become forgotten today.