Smith's most famous work is his Lensman series, but his first publication was The Skylark of Space. Smith went on to write a four-book series which is a defining work in the history of science fiction. Unfortunately it has not aged well and I do not recommend it.

Skylark Three - Osnome is under heavy attack by a foe intent on utterly destroying their entire race, so the Osnomians appeal to Seaton and Crane for help. They agree to help the Osnomians, and with the overwhelming military might of the Skylark, Seaton ends the war and enforces a peace treaty. But there is an even greater enemy: the Fenachrone, an evil race with aspirations of galactic conquest. Seaton and Crane go searching for help to defeat the Fenachrone, and discover the Norlaminians--a peaceful race of super-scientists. Although the Norlaminians cannot comprehend violence themselves, they readily supply Seaton and Crane with the necessary weapons to defeat the Fenachrone.