The Day After Roswell is an American book about extraterrestrial spacecraft and the Roswell UFO incident. It was written by United States Army Colonel Philip J. Corso, with help from William J. Birnes, and was published as a tell-all memoir by Pocket Books in 1997, a year before Corso's death. The book claims that an extraterrestrial spacecraft crashed near Roswell, New Mexico, in 1947 and was recovered by the United States government who then sought to cover up all evidence of extraterrestrials.
The majority of the book is an account of Colonel Corso's claims that he was assigned to a secret government program that provided some material recovered from crashed spacecraft to private industry (without saying where the items came from) to reverse engineer them for corporate use. Corso was a Special Assistant to Lt General Arthur Trudeau, who headed Army Research and Development, and was in charge of the Foreign Technology Desk. In this position, he would take technological artifacts obtained from Russian, German and other foreign sources, and have American companies reverse engineer that technology. The book contends that several aspects of modern technology such as fiber optics and integrated circuits were developed by using information taken from the craft.
Colonel Corso also claimed the world was "at war" with extraterrestrials and that the Strategic Defense Initiative project was part of that campaign that was successfully concluded in Earth's favour.
The book concludes with reproduction of information about Project Horizon, a 1950s US Army plan for bases on the moon.