The most widely quoted [foo fighter] sighting occurred on 23 November 1944 and involved the 415th, an American night fighter unit flying out of France. They seem to have been the location of most of the best-known 1944-5 reports and were the source of the “foo fighter” nickname.
On this date, Lieutenant Edward Schlueter was going from Dijon on an intercept mission to Strasbourg and Mannheim, flying mostly above the Vosges Mountains. With him were Lieutenant Don Myers and an intelligence officer, Lieutenant Ringwald.
(The Complete Book of UFOs, Hough and Randles)
The sky was clear and the American radar had detected no enemy presence in area. About 30 km from Strasbourg Lieutenant Ringwald… saw towards west a linear formation of eight to ten red fireballs moving at great speed.
(UFOs 1947-1987: The 40-Year Search for an Explanation, Evans and Spencer)
Ringwald was an excellent and experienced observer: he had just spotted a freight train miles away from their flight path, despite the fact that its boiler was shielded by blackout and only a plume of steam had given its location away.
The crew debated the lights. Were they misperceptions of stars? Could they be meteors? Perhaps their own aircraft was reflecting off clouds? They dismissed each idea in turn.
Then, as they closed in for the kill, the red fireballs simply melted into nothingness. Minutes later they reappeared, then vanished again. It was as if they were playing tag. The crew gave up and got on with their raid.
Many similar sightings followed. Radar stations and on-board radar in the aircraft showed that nothing was actually there. Yet the lights climbed up, chased the bombers, matched them for speed and manoeuvrability and then disappeared instantly. It is not surprising that the possibility of a “secret weapon” became popular…