This note contains spoilers for the book.

This "Medal of Honor" is even rarer than the current American one. Despite the title, it's a solar-system level award; humans haven't actually managed to leave the solar system yet.

They are, however, locked into a war with an alien species that showed up 50 years ago. Four space fleets from Earth nations met them, and they all attacked. The aliens fled, and the humans formed a world government. And got locked into a permanent state of war, even though the aliens probably never showed up again.

There's also a subplot about the greedy capitalists with no morals, and how the Church works with them. All in all pretty satisfactory. In the end of course the Sub-Lieutenant who wins the medal (fraudulently) ends up setting in train the necessary actions to clean up the whole mess.