"Half the Battle" is a short story by Harry Turtledove. It was originally published in the February 1987 issue of Stardate, and was subsequently reprinted in There Will Be War IX: After Armageddon, edited by Jerry Pournelle in February 1989. It has not been reprinted since.
Set in a post-Apocalyptic southwestern United States, over the course of five brief segments, the story follows the recovery of technology starting in the kingdom of Canoga, and then rapidly traces humanity's rediscovery of flight through the development of the Messerschmitt and the space shuttle. It ends with the launching of the first starship, built based on the designs found in a long hidden book: implicitly, a Star Trek guidebook, in keeping with the theme of Stardate.