Vanguard of the Doomed is credited as by Gerald Vance, an Amazing Stories house name shared by several authors. The actual author of Vanguard of the Doomed is unknown. It appeared in the February 1951 issue of Amazing Stories and can be read here at Archive.org.
A short-wave radio enthusiast and electronics engineer meets a girl over the air-waves. While she’s short and coy, the guy ends up absolutely head over heels for her, and she seems to like him. So when she cryptically signs off, telling him she’ll get in contact with him later if she can, then doesn’t show up for over a week, he worries begins to worry and decides to investigate.
What ensues is a tense, fairly action-packed post-war sci-fi thriller. Turns out the dame is the secretary of a mad scientist… who is actually an ex-Nazi posing as the mad scientist he’s done away with and using the mad scientist’s mad science to strike a blow for a resurrected Reich. Anyway, she’s stumbled on his secret plan to draw a planetoid referred to by astronomers and the media as “The Celestial Hammer”.
Remember the Max Fleischer Superman cartoon, where the astronomer has a magnet ray that he uses to get a better look at asteroids and meteors by directing them closer to earth and disaster ensues? Basically that, but the guy is doing it on purpose because he’s a Nazi and he’s gonna hold the world for ransom Cobra Commander style.
One interesting tidbit is that the Nazi villain is named Max Borzeny. Now, Borzney isn’t a real German name, but a thinly disguised spin on Skorzeny. Otto Skorzeny’s exploits in the war brought his profile much higher than his rank and responsibilities–he was larger-than-life boogeyman both feared and admired by Allies. The Borzeny in the story bears little resemblance to Skorzeny, but it is indicative of some of the mystique of SS Commando who, only a few years later, would be turned into ‘a real life pulp hero’ in Charles Foley’s hagiography Commando Extraordinary. Also worth noting, that despite being a relatively minor figure in the Reich, Skorzeny would go on after the war to basically become the real life Red Skull.