I know a guy whose father was in the army back in the early 1960s, and one of their infantry training schools involved a simulated night-time exercise in which they had to go out into the woods, set up a perimeter around a base camp, and keep the "enemy" from infiltrating the camp.
This guy apparently had a friend among the officers who knew how the "enemy" was planning to carry out their operations that night, so he tipped this group off with a warning: "They're going to creep through your area between midnight and 3 AM."
What this guy didn't know was that this same officer had issued a challenge to the infiltrators and told them that the forces defending the perimeter would know where and approximately when the attackers would try to sneak into the base camp. The "enemy" was apparently a phenomenal group of soldiers, and they didn't appreciate the officer's meddling.
The defenders in that sector dug their trenches, set up their trip wires, warning devices, etc., and hunkered down for the night. Midnight came and passed, then 1 AM, then 2 AM, etc. Nothing happened all night, and the infantrymen were convinced that the officer had been jerking their chain just to keep them on edge.
When the sun rose the next morning, each of the guys in that squad had an orange spot painted on the front of his helmet, courtesy of the vaunted "enemy" who had paid a visit during the night and passed them by without making a sound.
Heard a similar story of an exercise between a Navy Seal/Seebee squad and the Green Berets.
Seems during the mid '70s that a Seal/Seebee squad was to attack the Green Berets. During meeting discussing the rules for engagement, the Green Berets ridiculed the Seals and said they were highly overrated. The Seals didn't say anything, just laughed at themselves along with the Green Berets. The next morning, the Green Berets had alertly made sure that no Seals got through, but then noted that all of their footlockers had "Go Navy" stickers plastered all over them.
They must have all been sleeping then. big no-no! I'd thrash the lot of my platoon if they embarrassed me like that. I take it they had no sentries posted then?
My brother had a simular story to tell. Only it happened during the very early 50s during the build up for Korea at Indian Town Gap. He was assigned to a recon unit in a war game. they were assigned to locate the opposition tanks and report back. Instead they painted the white stars on the tanks red and returned. The next day the whole platoon was called on the carpet for destroying government property but no one owned up to doing the deed and nobody ratted so they all got restricted to barrecks, KP, etc. etc. Then they were shipped out and got to fight for real.