Gallun (rhymes with "balloon") was born in Beaver Dam, Wisconsin. He lived a drifter's existence, working a multitude of jobs around the world in the years leading up to World War II. He sold many popular stories to pulp magazines in the 1930s. "Old Faithful" (1934) was his first noted story. "The Gentle Brain" was published in "Science Fiction Quarterly" under the pseudonym Arthur Allport. Another of his pseudonyms was William Callahan.
See http://manybooks.net/authors/gallunr.html for a free e-Book version of "The Planet Strappers".