What's it about?
Setting: Military Cold War Europe
"After World War II, Germany was split into two countries, East and West. The citizens of the two nations lived as enemies. In 1967 humanity encountered an alien life form on the moon, the BETA [Beings of the Extra Terrestrial origin which is Adversary of human race], and war broke out. Six years later, the BETA landed in Kashgar, in Central Asia. In the midst of the Cold War, humanity was thrust into a fight for its very survival. And ten years later, the war's front lines were in the German Democratic Republic, East Germany. The BETA's advance into Europe put East Germany in a desperate position, and the Ministry for State Security, the Stasi, put a surveillance system in place throughout the country to maintain their fighting forces. Fear of the state caused the people to monitor one another. The result was a mad society in which parents blew the whistle on their children, children on their parents, husband on wife and wife on husband. We believed in no god, and had no one else to believe in. Our only choices were to die on the battlefield, to die in the purges, or to live like machines."
Did you make it through that entire explanation without skipping ahead to look for a tl;dr? If so, Schwarzesmarken may be the anime for you!
That paragraph is the first 90 seconds of the show, a pre-credits sequence of pure monologue exposition because "show don't tell" is a principle Schwarzesmarken has decided doesn't apply when your premise is as straightforward as "oppressive government x (alien invasion + mecha) - any shred of happiness ". I won't be watching beyond episode four, but that's because of the narrative approach rather than the fanservice.