Well, technically it’s Lest Darkness Fall & Related Stories because this edition has a short story by S.M. Stirling in it, and if it’s the one I’m thinking of it’s also worth perusing. Lest Darkness Fall is one of the classic ‘time traveler changes the past’ stories; not least because it doesn’t assume that the hero is going to be able to recreate every technological innovation. L. Sprague de Camp was simply too freaking brilliant to fall into that particular trap. Lest Darkness Fall is almost eighty years old, and doesn’t look a day over thirty. I don’t even know why I’m recommending it; surely everybody reading this has read it already, yes?
Anyway: say farewell to The Complete McAuslan.