The modern UFO phenomenon started in America in the summer of 1947, when a prosperous businessman and private pilot named Kenneth Arnold spotted nine strange "disk-shaped" craft flying over Mt. Rainier in Washington State. His story made headlines across the nation, and the "UFO Era" was born. Over the next five years (1947-1952) many of the most famous UFO sightings in American history took place, and the US Air Force became concerned enough to launch a top-secret investigation of the sightings. Originally called "Project Sign", it concluded in 1948 that UFOs were interplanetary spacecraft from an advanced alien civilization. The Pentagon rejected this analysis, fired most of the staff, and renamed "Project Sign" as "Project Grudge", with the new mission being to debunk all UFO reports. However, in the early fifties the wave of UFO reports reached an all-time high (it has never been equalled since), and even some high-ranking officers in the Pentagon became convinced that SOMETHING strange was taking place in America's skies. So they reorganized "Project Grudge" into "Project Blue Book", and appointed a young but talented USAF Captain, Edward J. Ruppelt, to supervise the new, beefed-up UFO investigation.
From 1951-1953 Ruppelt presided over a kind of "golden age" of UFO reports. Under his guidance Project Blue Book objectively and thoroughly investigated each UFO report it received. Ruppelt was naturally skeptical of UFOs, but he also didn't dismiss the subject as "nonsense", and he insisted that his staff take the phenomenon seriously and remain open-minded when they were investigating UFO cases. As a result he wasn't afraid to label a case as "unsolved" or "unexplainable" when he or his staff couldn't find a "normal", rational explanation for a sighting. Ruppelt managed to investigate some of the most famous UFO cases in history, including the "Lubbock Lights" in Texas, which were seen by science professors at Texas Tech University, and which were photographed by a Texas Tech student. He also investigated the two famous UFO "movies" shot in Utah and Montana on old home-movie cameras. The Montana film was shot in 1950 by the manager of the Great Falls minor-league baseball team, and it showed two bright objects moving rapidly across the sky above the local baseball stadium. The Utah film was shot in 1952 near the Great Salt Lake by a professional Navy photographer. The film shows 12-15 bright objects (which bear a remarkable resemblance to the Montana film) flying in formation in the clear blue sky. The US Navy analyzed both films and, as Ruppelt writes, they judged that both films showed "genuine" UFOs - not birds, not planes, nor any other "normal" phenomena. Ruppelt also investigated the great "Invasion of Washington" in July 1952 when UFOs were seen above the nation's capital and were detected by radar at two airports in Washington. (The "Invasion of Washington" made front-page headlines across the country, and even President Truman called Ruppelt personally and wanted to know what was going on).
Ruppelt left the Air Force in 1953 for a civilian engineering job, and in 1956 - much to the displeasure of the Air Force, which had forced Project Blue Book to return to debunking all UFO sightings - he wrote "The Report on Unidentified Flying Objects". This book is still considered to be the "classic" account of UFO sightings in the late forties and early fifties, and it also provides a wealth of information about how the US government and military viewed the UFO "problem" during those years. Ruppelt is a good writer, and the book is well-written and filled with many interesting stories and anecdotes from pilots, scientists, military officials and others whom Ruppelt talked with about UFOs. Ruppelt himself was an "open-minded skeptic" and he doesn't include any explanations for what UFOs might be - he simply describes his investigations into the subject and his experiences as Project Blue Book's supervisor. I should add that in 1960 an "enlarged and updated" edition of this book was published with three additional chapters written by Ruppelt. In these new chapters Ruppelt is far more critical of the UFO phenomenon than he was in the original 1956 edition, and basically states that all UFO sightings are explainable in conventional terms. Needless to say, this "revised" 1960 edition caused considerable controversy when it was published, with some critics claiming that the Air Force pressured Ruppelt into adding the three new chapters. Others claim that Ruppelt's investigation of the weird New Age "contactee" UFO movement in California soured him on the entire UFO phenomenon; at any rate, I would recommend buying the original, "unrevised" 1956 edition for a better (and possibly more accurate) view of Ruppelt's experiences as the Air Force's chief UFO investigator. This book is an absolute "must" for any UFO buff or anyone who's interested in the early history of UFO sightings in America. Highly recommended!