'Project Blue Book' Season 2 finale will delve into the true story of Operation Mainbrace UFO and USO sightings

Before spotting flying saucers, a naval fleet actually observed a triangular, submerged udentified craft emitting blue lights. What was it?

                            'Project Blue Book' Season 2 finale will delve into the true story of Operation Mainbrace UFO and USO sightings
Aidan Gillen as Dr J Allen Hynek and USS Wisconsin Admiral (History)

Spoilers for Season 2 Episode 10 'Operation Mainbrace'

On tonight's Season 2 finale of 'Project Blue Book', we see Dr J Allen Hynek (Aidan Gillen) and Captain Michael Quinn (Michael Malarkey) set off for a naval fleet amid Denmark and Norway, after crew members claim to have seen a giant triangular craft emerge from the ocean emitting blinding blue light. The show then sees the Blue Book duo investigate the case upon Senator Kennedy's orders, and face off with a rogue Admiral who believes this is a Russian Third World War attack. In the end, Quinn sets out on a submarine and discovers its source — a bioluminescent thread of light that goes unexplained. Pretty much the way these real-life sightings and the source of the blinding light still remain unexplained.

According to the website UFO Casebook, "A particularly interesting series of UFO reports came from the vicinity of the 'Operation Mainbrace' NATO maneuvers held in September 1952," in the same Denmark-Norway region as we see on the show. The website adds: "The maneuvers commenced September 13th and lasted twelve days. According to the US Navy, units of eight NATO governments and New Zealand participated, including 80,000 men, 1,000 planes, and 200 ships." British Admiral Sir Patrick Brind was the director of what has been labeled "the largest NATO maneuver held up until that time."

On September 13, 1952, Danish destroyer Willemoes was participating from the north of Bornholm Island, and later that night, the ship's Lieutenant Commander Schmidt Jensen and several members of the crew witnessed an unidentified, triangular object speeding towards the southeast. Commander Jensen reportedly estimated the speed at over 900 mph and the object carried a bluish glow, which wasn't an isolated incident, by the way. The following week saw four other similarly curious sightings witnessed by credible observers. While all occurred on or about September 20, the reports' authenticity isn't up for debate, since the British cases were reported officially by the Air Ministry.


One of the reports was that of a silvery object following a British Meteor jet aircraft, as it was returning to the airfield at Topcliffe, Yorkshire, England. On its approach to land, it swayed like a pendulum and once the Meteor began circling, the alleged UFO stopped moving. Soon it took off high speed and disappeared to the southeast. On the show, when the crew first witness the bizarre phenomenon, they too see the giant triangular charge at them before diving into the water right before the crash.

On September 20, an aircraft carrier participating in the Mainbrace maneuvers spotted yet another silvery, spherical object, photographs of which albeit taken, remain undisclosed. 'Project Blue Book' author and one of the Air Force officials aboard the titular investigation, remarked: "[The pictures] turned out to be excellent . . .  judging by the size of the object in each successive photo, one could see that is was moving rapidly." Even though color photos of the UFO were taken, only a poor print of the photos remains in the investigation's files, that too without any analysis report, claims UFO Casebook.

Similar incidents happened on the same day, at Karup Field, Denmark, and the next day, September 21, above the North Sea. On September 27, or 28, widespread UFO reports arrived from all over Western Germany, Denmark, and southern Sweden. From a "bright luminous object with a cometlike tail" near Hamburg and Kiel. to "three satellite objects reported moving around a larger object," and a "a cigar-shaped object moving silently eastward" was also alleged, claims the outlet. Considering the U. S. Navy and Air Force Intelligence, and the RAF were studying these incidents, it's possible that the findings might be preserved somewhere. But for now, the mysterious sightings of 'Operation Mainbrace' remain unexplained. 

'Project Blue Book' Season 2 finale aired on Tuesday, at 10 pm on History.

If you have an entertainment scoop or a story for us, please reach out to us on (323) 421-7515