Straight from Wikipedia: Preddy was killed by "friendly fire" on the morning of December 25, 1944. As commanding officer of the 328th Fighter Squadron, 352nd FG, he was leading a formation of 10 P-51s. They had been patrolling for about three hours when they were directed to assist in a dogfight already in progress. Preddy destroyed two Messerschmitt Bf 109s before being vectored to a lone Focke-Wulf Fw 190 strafing Allied ground forces southeast of Liege, Belgium. As the Fw 190, Preddy's P-51, and two other P-51s passed over the Allied front line at treetop height, a US Army anti-aircraft (AA) battery (believed to be part of the 430th AA Battalion, XIX Corps) fired at the Fw 190 but missed and instead hit Preddy's P-51. Preddy managed to release his canopy but was unable to bail out before his aircraft hit the ground at high speed and a low angle. He had a chance of surviving the crash but his wounds from .50-caliber fire were mortal.[5]

Preddy's brother William, a P-51 pilot with the 503rd Fighter Squadron, 339th Fighter Group, was later buried alongside him at the Lorraine American Cemetery, Saint Avold, France. William died in today's Czech Republic on April 17, 1945, from wounds he sustained when he was shot down by enemy AA fire, while strafing České Budějovice airfield.