This story I am sure was in Analog. A confederation of aliens come to earth and are able to break through a force field enclosing earth. The field was put there by aliens since they were not able to break earth's defenses in an older war. Earthlings appear completely non-technological, and the good aliens think they may at least be able to dress them up to be scary. One alien falls in shaft through hundreds of stories of tech before being saved. They bring down the force field and earth celebrates. Even the horses and dogs have conversations about it. Earth has not been idle during their imprisonment. They take on challenging the evil alien empire by moving the earth into space, and they take the moon along. I remember a cute seen where the human says he is making ice cream, but he is not sure he has enough for a large alien. The alien tries to hunch up, but it not sure if "ice cream" is something good or if it is used to remove reluctant teeth. A really great story.