You choose to enter the main ditch on the east side where the branch ditch goes down to the tower on the water.
Good choice. It appears you scouted things out before you advanced on the fort. This is one of the easiest places to get into the ditch.
If you are lucky, you don’t even need a rope. The other easiest place is on the west side of the fort where the ditch goes down to the tower on that side.
