I suppose every movie buff or Steve McQueen fan is familiar with the feature film, "The Great Escape." In the film we see teams of diggers building tunnels out of the barracks, some escaping, most finally caught, and a large group summarily executed.
The POWs were all airmen, and the wiliest of the wily, having tried desperate escapes before. The camp was run by the Luftwaffe who decided to collect all the hard chargers in one camp, deliberately designed to make escape impossible. The feature film concentrates on the men and their plan and skips over some technical details that this documentary fills in.
One example. The Luftwaffe designed the camp to be escape-proof and one thing that helped was its actual location. It was surrounded by soft red sand. If anyone tried to tunnel out, the red sand on his clothing would give him away, as would any piles of sand found within the compound. The feature film shows us how the men got rid of the sand from the digging, but doesn't mention that it was so distinctive. In the film, it looks like any other dirt.
Another example. The viewer of the feature film isn't faced with the fact that the Germans had microphones planted around the compound so that sounds of digging would be picked up. This forced the POWs to dig straight down, thirty feet under the barracks, before they could even BEGIN the tunnel outwards. As the narrator says, "This was no job for claustrophobics." If you used your credit cards to measure the depth of the shaft, you'd need 103 credit cards, so my pocket calculator says. Then, of course, you need to build a ladder to climb up and down the shaft. The feature film seems to minimize these technical difficulties.
One more example. In the feature film the diggers are aided by lamps. Where did the lamps come from? Sometimes candles were used but more often the grease was skimmed off the top of the fatty mutton soup the POWs were fed and that provided fuel for primitive lamps.
Seventy six men got out, not as many as had been hoped. When the Germans discovered the escape was in progress, the men back in the barracks began burning all their carefully forged documents, maps, and currency. Just three men reached freedom, two Norwegians and a Hollander. Hitler ordered all of the captives to be shot, in violation of the Geneva Conventions, but his generals whittled the number down to fifty. The Luftwaffe camp commander was so appalled by the executions that he allowed the airmen to build a small memorial outside the camp.
The framing story has a handful of battlefield archaeologists excavating the remains of the tunnel. It's far less interesting than the story of the escape itself.