Project Blue Book Case #69. On July 29, 1947, an unidentified object was observed at Hamilton Field — an Army Air Forces fighter interceptor base in Marin County, California, just north of the Golden Gate Bridge. As Case #69, this was among the very earliest entries in Blue Book's archive, from the explosive first summer of the modern UFO era.
Hamilton Field's P-51 Mustang and P-80 Shooting Star fighters were tasked with defending the San Francisco Bay Area. The base's pilots were combat veterans of World War II, trained to identify aircraft at extreme speeds and distances. July 29, 1947, was during the peak of the original wave, with reports flooding in from across the country. The case was classified "Unknown" — one of the founding entries from the very birth of the UFO era.