I wonder if you can help me to find a movie.

I watched it when I was young, and I do not remember the name only a few parts

It is about French soldiers in world war being captured by the Germans and they are 2 or 3 soldiers escaping but they being recaptured and so on and on.

A few things I remember , once they stole a German tank and they drove it into a German shop keeper saying heil Hitler etc..
Another part is once they were in the war camp they tried to escape behind mattresses, i.e. they moved mattresses from one floor to another and behind them there were soldiers,

I also remember one of the times when they escaped was when they were fixing the railway for the germans.

If you can help me I would appreciate it

Thanks