Glen Miller disappeared over the English Channel today 15 December 1944.

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From his wik-"Miller's travel orders did not authorize him to board a "casual" flight and he did not report his intentions to his chain of command, so SHAEF was in the dark concerning Miller's whereabouts. Although AAF and RAF combat missions flew that day, as well as numerous transport planes, the RAF Training Unit at RAF Twinwood Farm, near Bedford, had stood down, but the aerodrome was open. At 13:45 hours (1:45 PM), Morgan landed at Twinwood, boarded Baessell and Miller, and took off at 13:55 hours (1:55 p.m.). The UC-64 and its occupants were never seen again. The next morning, the Battle of the Bulge began. The Eighth Air Force and SHAEF did not realize that the UC-64 with Miller aboard was missing until three days later, on Monday, December 18, 1944."

More there.


Since the Battle of the Bulge began the next day in the The Ardennes region of Belgium, Luxembourg, and France SHAEF was very busy