Lest Darkness Fall Author:L. Sprague de Camp One minute archeologist Martin Padway is casually ambling through modern Rome. In an instant he is inexplicably hurtled back through time to 6th century Itay-just before the Dark Ages. With one foot firmly rooted in the 20th century, and the other planted tentatively in the Gothic Era, Padway-now Martinus Paduei, Quaestor-uses his wits and his k... more »nowledge to change the course of history« less
Not at great example of this sub-genre, but it is entertaining and more realistic. I checked on Fantastic Fiction and this novel is one of the first three books he wrote, in 1941.