The movie I have watched more times than any other As the other reviewers have suggested, one of the greatest movies ever made. As it does not need any further endorsement, I thought I might provide a few interesting sidelines.
The book on which the movie is based, by the Australian author Paul Brickhill, is equally good. Brickhill is a writer who specialised in world war 2 true stories; he also wrote 'Reach for the Sky'(the story of Douglas Bader) and 'the Dambusters', both of which were also made into stirring films. Brickhill is a master story teller whose books rush on breathlessly and really do defy the reader to put them down.
In the book, as was actually the case, American characters hardly figure at all; obviously the introduction of characters such as Steve McQueen's Hilts was intended to make the movie more palatable for US audiences. For once this tampering with the source does not at all prove a negative. This is obvious when you consider that easily the most memorable sequence in the film, McQueen's attempt to leap the barbed wire border on his motorbike, is the fruit of this invention.
I think that the inclusion of James Coburns' character, Sedgewick, was made in acknowledgement of the author's nationality. Brickhill was an inmate himself at the prison camp where the great escape took place. Sedgewick is evidently an Australian, though you would never know from Coburn's egregious attempt at an Australian accent.
Richard Attenborough's character, Bartlett, the big X or escape coordinator, is based on the Roger Bushell of the book. Why change the name from Bushell to Bartlett? Just a case of someone justifying their paycheck, perhaps.
Additional dialogue for the movie was written by James Clavell, author of King Rat, Shogun etc. This is pure surmise, but I'm almost certain which scenes are his contributions: those where Bronson and Coburn attempt to escape with the Russian slave-labourers; when Wing Commander Day, asked by the commandant why he, an English gemtleman, is growing vegetables, not flowers ('you can't eat flowers'); and the one where the Americans distill some bootleg grog to celebrate American independence day.
Finally an opinion on the music of Elmer Bernstein. It seems to me that it, like Mozart's, can be immediately atrributed to the composer, even on a first hearing, obviously without a suggestion that they are in any way repetitive. Consider the music for this movie, the Comancheros and the Magnificent Seven.