> During the Battle of the Bulge in WW2, the Germans infiltrated Allied lines with fake officers who would give orders that messed up the Allied command structure. The fake officers were Germans who spoke perfect English and had often grown up in the US.

This did not happen.

However, at the time, in the massive confusion of a wholly unexpected large-scale German attack, rumours and paranoia were rife, including that of German parachute landings behind the lines.

A result of this was the widespread belief, at the time, that Germans had infiltrated and were giving fake orders, etc, and so troops were indeed widely being suspected, and asked for example the capital of Illinois and so on (and being asked by privates, who did not know that the actual capital is Springfield rather than Chicago, to generals, who did know).