The Ghost Army at Ludendorff Bridge

The Ghost Army at Ludendorff Bridge was a mysterious battle which took place during March of 1945, apart of the ongoing battle of Remagen
During a foggy night in march of 1945. American troops on the sourthern end of the bridge came under fire by an unknown enemy force. The US troops scrambled and attempted to fire back but were unable to identify any valid targets. The Americans suffered an undisclosed number of casualties as the battle lasted through the misty night. When the fog cleared and the sun came up the gunfire ceased. There were no recovered bodies of enemy combatants and all reminents of an attacking force had seemingly vanished.
There is a lot of speculation on what occured. From the attack being carried out by the elite Waffen SS "Werwolf" troops, to more supernatural explanation such as the ghosts of fallen German Soldiers. Survivor accounts either claim to have made no visual contact with the attacking force, while others claim they saw German troops in the fog.