This note contains spoilers for the book.

The "Bolo" concept is of course from Keith Laumer.

This is a collection of stories, which follows the development of emotion-capable Bolos from the lab out into the field, until they save not just the human race, but their implacable enemy as well. Of course, along the way they also nearly destroy that enemy, which nearly destroys us.

These are kind of a coming of age story for the Bolo AI capability. They eventually reach the point where they'll say "no" to their commander; luckily late enough that they don't immediately all get scrapped. The one remaining one (at least that we know about; it's very unlikely there's really exactly one planet left with population) will continue to keep the enemy from killing the humans—while allowing them to live on the same planet. And there's a nice epilog where another division of the re-expanding humans meets up with the humans who have actually made peace with the enemy with whom we wiped out nearly all the civilizations in the spiral arm.

Does make me think of the "Spock" problem, though—always worrying at the limits of the AI capabilities.