The problem is that the director saying that makes no difference to the perception of the film by the huge majority of the audience, and putting a brief on screen 'disclaimer' at the end (or was it the beginning) does nothing to help.
A good war film should be first and foremost a good film, U-571 does not fall into this category for me. It is an extremely silly film, even if nobody had ever captured a German code machine.
<<<snip>>>
And
"At the time of its release, Tony Blair condemned U-571 in parliament as an insult to the Royal Navy. A far more entertaining response would have been for Britain to fund a big-budget revenge epic, in which a small platoon of foppish yet plucky Brits swans over to Vietnam in 1968, defeats the Viet Cong, and wins the war. Moreover, it would be nearly as accurate as this."
Finally.
"The director actually has the audacity to end on a title card dedicating his film to the memory of the real sailors who captured Enigma machines. Yes, that same memory he has just desecrated. This is exactly the most tasteless gesture the film-makers could have made."
In any case the disquiet over U-571 pales into significance when compared to the furore over 'Objective Burma' when it was released, then withdrawn, on this side of the pond.