There's a short story by Harry Turtledove about aliens that have mastered gravity (because, as it turns out, it isn't that difficult to do) but all of their oth

There's a short story by Harry Turtledove about aliens that have mastered gravity (because, as it turns out, it isn't that difficult to do) but all of their other technology is pre-industrial revolution level. They try to invade Earth in 2039 - I won't spoil what happens next. It's a fun read. https://en.m.wikipedia.org/wiki/The_Road_Not_Taken_(short_story) https://en.m.wikipedia.org/wiki/The_Road_Not_Taken_(short_st...