This story comes from my father, who was in the army and stationed in Germany just after WW2. He swears to this day it is true, and it sends shivers down my spine.

One night in his barracks, he was in his bunk, along with a lot of soldiers, ready to go to sleep for the night. The room was dark apart from a small amount of light coming from a small glass window above the main door to the dormitory. My dad is lying in his bed and from the door he sees an officer enter the room and approach each bed as if he is doing an inspection of the dorm. He stops at each bed, including may dads. At this point my dad is frozen in his bed as he realises there is something not quite right about what is happening. My dad, being a hardy soul, soon goes to sleep. In the morning, the soldiers go to the mess for their breakfast, where there is a commotion about some incident that happened during the night. He soon finds out that the sentry man at the main gate of the compound had been found in the morning lying in a terrible state clutching a telephone receiver which had been ripped out of the telephone. What had happened during the night? Well apparently the sentry man had spotted what looked like an officer approaching the main gate in the dead of night. The sentry man attempted to ask the officer his business, and at this point the officer kept walking, right through the gate. My dad reckons this is the officer he had seen in his barracks during the night.
I am 43 years old, and my dad still swears to this day that this actually happened.