A computer had projected that yesterday was supposed to be the day that aliens from outer space were going to arrive.

I always wanted something on the order of the story written by Harry Turtledove, ( an ‘alternate history’ author who also wrote “The Guns of The South” which had time travelers supplying AKs to the Confederacy, but I digress)  titled “The Road Not Taken”  where aliens with anti-gravity and faster than light spacecraft, but armed with nothing more than muzzle loading arms, arrived to ‘conquer the Earth’.