A novella by Lester del Rey from the pages of Astounding Science Fiction August 1955.
It seemed Earth was a rich, and undefended planet in a warring, hating galaxy. Things can be deceptive though; children playing can be quite rough—but that ain't war, friend!
Lester del Rey (June 2, 1915–May 10, 1993) was an American science fiction author and editor. Del Rey is especially famous for his juvenile novels such as those which are part of the Winston Science Fiction series, and for Del Rey Books, the fantasy and science fiction branch of Ballantine Books edited by Lester del Rey and his fourth wife Judy-Lynn del Rey.
Lester and Judy-Lynn del Rey
Source: Project Gutenberg
Reformatted for my enjoyment, and hopefully yours!