Health issues led to his discharge in August 1941 .
According to papers in the SOHS Archives , Bretnor 's military background included service in the last cavalry unit in the U.S. Army .
Health issues led to Bretnor 's discharge in August 1941 .
According to papers in the SOHS Archives , Bretnor 's military background included service in the last cavalry unit in the U.S. Army .