To access the fort, there were smaller paths divided from the main route, each heading towards one of each of the nine hills. William could tell how hard it was to climb upwards towards the fort using these hills. But for a reason, the chariots down there didn't face any trouble, kept marching up as if they were walking on flat land.
"They must have used some sort of an array on these hills, or else these huge caravans won't be able to make it!" William developed more admiration towards all the thoughts given by the leaders of this fort, even to this small detail.
As long as there was no gate to knock down, no clear and easy path towards top, it was safe to consider this fort impregnable.
The only way to take such a fort would be from inside, or from air. William knew finding aerial monsters in this tiny world would be rare.