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My wife read a book decades ago where the most feared and vicious alien race in the galaxy is a race that looks kind of like a teddybear. They arrive, and start to descend upon earth to conquer it...with their muskets, cannons and dirigibles. I think it's the US Air Force that intercepts them with fighter jets and, needless to say, blows them away. Other races show up to see what has these 'teddybears' so terrified...figuring if Earthling can terrify the t-bears, then maybe they can help defeat the "scourge of the universe" (which is the t-bears, as they have gunpowder and nobody else has anything even close to that). However, space travel is apparently 'simple' and the alien races are stunned that Earthlings haven't figured it out.
Anybody know what story I'm talking about? I'd like to read it.