On the level 'Sabotage', The objectives are: go to post room, Take
pictures of rocket, radio for bombers, escape. When in the Exercise
Yard, there should be a guard patrolling up and down the side of the
fence, go up to him and press 'talk', and you can bribe him with 100
currency to: Leave the Post room door unlocked, and for the radio part,
he will give you a steel key. I don't know what he does for the other
objectives, but i will try right after i have wrote this. Oh yeah, The
Guards name is 'Gruber' and will not do what i just listed if you come
up to him in a German uniform, and he WILL do it even when you are not
supposed to be in the exercise yard.