ALWAYS THE BLACK KNIGHT
Kyning was a dreamer and he dreamed often of winning. But his role in the play was always the black knight - and the black knight always lost. Now a "perfect" planet was in danger of conquest by a man Kyning had taught to be a winner. Suddenly Kyning had to shake free of his dreams and face a reality that contained his death - and that of a planet!
Serialized in Amazing June & August 1970. A good novel by a little-known (these days) SF fan and author.