You are in C

Your 3rd difficulty! You'll have to get through the first portcullis See a cross-section of the gate.

I'm afraid so ! but you are being stuck because of a metal portcullis meanwhile ...

Be careful! on each side of the gate, on each tower, through loopholes, you are being shot. Do not stay too close of the portcullis, you'll be likely to be scalded (not by oil) by the machicolation which is above you.

Let's say you managed to get through the first portcullis.

Admit that it is improbable.