German POW Karl Rabe, in 1943:

Each evening big empty plywood boxes for the handling of bread were placed between the inner and outer main camp gates. One night he got into one of the boxes and with a handmade saw started to saw his way out of the box at a time when he calculated no guard was around. However in the silence of the prairie night his sawblade together with the vibrating of the pliable plywood made a terrible noise. Soon a sentry came to the box to watch he was joined by about twenty guards who watched him emerge from the box. His hair was shaved and he received two weeks detention.

Later in the heat of the summer Rabe having studied the drainage system the camp, decided to escape via the storm sewers.

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Escape attempt number three involved power lines connecting the camp buildings. On a rainy night Rabe attached two wheels with handles protruding on top of the wires and rolled off into the night.

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The most ambitious escape attempt by this escape-a-holic was the preparation of a hot air balloon to fly over the barbed wire.

Read the omitted details (along with an earlier escape in Ontario) at the u-35 profile. Original source: David J. Carter's POW - Behind Canadian Barbed Wire.