[Ingtar]

The number who were caught was dictated by the real escape the book was based upon.

[Dr. Sivana]

The number who were caught was dictated by the real escape the book was based upon.

I know, but they did an exceptional job of ending on an upbeat note, making even the failed escapes important for the war effort. Compare that with Stalag 17, which was by comparison the downer of a movie one would expect from a POW camp drama.