Hokas Pokas! — Poul Anderson; Gordon R. Dickson

They're Baaaack!

When a human thinks he's Napoleon Bonaparte, it's time to get out a straitjacket. But when a Hoka thinks he's Napoleon Bonaparte, you'd better believe it! Particularly since there'll be hundreds of other Hokas around who know for a fact that they're the French army, man amis, even if they're on another planet light years away from Earth, and the forces they're facing aren't the British but very nasty warlike aliens who by all reason should be expected to make mincemeat out of the Hokas.

But when it comes to Hokas, reason does not compute.

These friendly, fuzzy aliens who resemble large Teddy bears have a very vivid imagination and have never quite grasped the difference between human fiction and reality, or (in the present case), between past history and the much later and rather different present. Always bet on the Hokas. Even when a young lad and his Hoka tutor find themselves stuck on a planet where they seem to be scheduled to fulfill an ancient (and lethal) prophecy that neither of them had ever heard of until now, Hokas as usual find that reality is merely optional and the good guys - and bears - always win, quicker than you can say