Triplanetary by E. E. “Doc” Smith is the opening volume of the Lensman series — one of the most ambitious space opera sequences in science fiction history. Originally serialized in Amazing Stories in 1934 and later revised to serve as the series prologue, the novel opens with a cosmic conflict between two ancient alien races who have been using humanity as pawns across all of recorded history, before launching into a far-future interplanetary adventure of staggering scale.
Smith essentially invented the conventions of space opera — fleets of faster-than-light battleships, galaxy-spanning civilizations, and heroes of almost godlike capability — and Triplanetary remains the foundation of that legacy. Download the free EPUB to experience the ur-text of cosmic adventure fiction.