Every fifty yards along the fence was a stolid, squat wooden tower.

These were manned around the clock by humorless and unbribable machine-gun crews, goons, with Schmeisser machine pistols hung around their necks.

Ten feet inside the main fence the Germans had strung a thin strand of wire from wooden stakes. This was the deadline.

Anyone crossing that line was assumed to be trying to escape, and would be shot. At least, that was what the Luftwaffe commandant told each prisoner upon arrival at Stalag Luft Thirteen. The reality was that the guards would let a prisoner, who donned a white smock with a red cross prominently centered on it, pursue a baseball or football if it rolled to the exterior fence, although sometimes, for amusement, they would wave a prisoner after the item, then fire a short burst into the air above his head or into the dirt at his feet. Walking the deadline was a favorite kriegie activity; the airmen would pace endless laps at the limit of their confinement.

The May sun rose rapidly, warming the faces of the men gathered on the parade ground. Tommy Hart guessed they had been standing in formation for nearly four hours, while steady processions of German officers and enlisted men had passed by, heading toward the collapsed tunnel. The enlisted men carried shovels and pickaxes. The officers wore frowns.

"It's the damn wood," a voice from the formation spoke.

"It gets wet, it gets rotten, won't hold up a damn thing."