The book is well regarded, and described by one critic, Richard A. Lupoff, as the best of Edgar Rice Burrough's non-series "scientific romances".

"[2] The prologues to both parts, "The Moon Maid" and "The Moon Men", constitute a future history, effectively Burroughs' vision of what the 20th century held in store for humanity, which could be considered a kind of retroactive alternate history—a genre rare in Burroughs' writings and a bit reminiscent of such works as H. G. Wells' The Shape of Things to Come.

As envisioned by Burroughs, there would follow many decades of unceasing worldwide fighting at various locations and at various intensities until a great outburst in 1959, leading to eight years of all-out war.

The British-American domination of the world is imposed by the International Peace Fleet, made up of airships, which is given a complete global monopoly of armed force.

In Burroughs's vision, the Anglo-Saxon victory in 1967 is immediately followed by the first sending of a crewed spacecraft to the Moon—Burroughs having come very near to the actual 1969 date of the Apollo 11 Moon landing.

The spaceship is seen taking off in a blaze of worldwide publicity and celebration, with the war's Anglo-Saxon victors seeking to provide a sense of common purpose to the forcibly unified world.

From the global point of view, the space venture horribly boomerangs by bringing the evil Earthling genius Orthis into contact with the malevolent Kalkars of the Moon, though the disastrous results would become evident only much later.