•Why it earns a slot
The story earns its place by inverting the standard 1950s science fiction war narrative: the apparent coward turns out to hold the most powerful weapon in the galaxy, and the decorated hero must unlearn fourteen years of righteous violence to become useful, making it a rare Cold War-era SF story that treats pacifism as a hard-won technological and philosophical achievement rather than weakness.
Earth appears cowardly and neutral while humanoid worlds bleed in interstellar wars, but a returning veteran named Duke O'Neill gradually discovers that Earth's pacifism is not timidity but a sophisticated, adult strategy backed by a physics-defying weapon that can teleport enemy fleets to the far end of the galaxy. The story follows O'Neill's disillusionment on ruined Meloa, his return to Earth, and his slow conversion from bitter warrior to reluctant agent of Earth's quiet diplomacy, while parallel threads show alien princes, scheming federation commanders, and vengeful rulers all stumbling toward the same lesson: that war at interstellar technological levels produces only mutual ruin. The final revelation is that 'victory' is not conquest but the ongoing capacity to face ever-larger problems without fear.
This distillation is written from the freely available original, which is always the better read when you have the time: gutenberg.org.