Cover art by Chris Foss (Panther Science Fiction, 1972).
Triplanetary was serialized in Amazing Stories in 1934.
The planets Arisia and Eddore were at war for control of the Universe. The battleground was a tiny, backward planet in a remote galaxy. Earth.
Only a few Earthlings knew of the titanic struggle, and of the strange, decisive role they were to play in the war of the super-races.
Here is the beginning of "Doc" Smith's famous Lensman series – the celebrated adventures that set the standard for all science fiction.
E. E. Smith (1890–1965), also Edward Elmer Smith, Ph.D., E. E. "Doc" Smith, Doc Smith, "Skylark" Smith, and (to family) Ted, was a food engineer (specializing in doughnut and pastry mixes) and early science fiction author who wrote the Lensman series and the Skylark series, among others. He is sometimes referred to as the father of Space Opera.
E. E. Smith. Wikipedia.