Lester Del Rey 
And There Was Light 

When the enemy believes the worst of you, they won’t settle for anything except the worst! Volcek believed his weapon would be humane, and less destructive than the dreaded fusion bombs.

Lester del Rey was an American science fiction author and editor. He won the Balrog Award, the E. E. Smith Memorial Award for Imaginative Fiction, and he was a SFWA Grand Master.