Quote Originally Posted by Brother Oni View Post
As far as I'm aware, the angle of catapults is adjustable (if all else fails put them on a slope), thus making it easier to launch stuff into the fort itself. Showers of small stones (the equivalent of grapeshot), flaming oil or dead animals would soon make the inside of the fort extremely unpleasant for the defenders.
Is there any evidence of people actually shooting loads of pebbles from catapults? Gravel has crappy aerodymanics, being small, light and having lots of irregular shapes. I'd think the range you could get from such a load would be really quite low, low enough to put the crew well into the range of unfriendly people with bows. Particularly if one fires the gravel on a highly parabolic trajectory.

I'm aware of onagers firing ~four or five inch diameter rocks certainly, but that's a very different thing than showers of small stones. That's one fairly big stone shattering shields and rib cages like twigs.

As with any siege, if you can't breach the walls, then the main assault is going to be focused on the gates. I know the celts had an alleged trick of throwing hornet nests into roman formations to break them up, but without those, I'd think a tetsudo would allow the Romans a better chance to clear out each ring of the fort, a layer at a time.
The testudo has always struck me as a horrible formation to actually fight from. There's no space for anybody in it to fight, move, or even see all that well. If one uses the variant with the flanks covered by shields as well, any advance must be painfully slow. IIRC the general Roman deployment was about one man every five feet or so, and the testudo was really only used in very specialized circumstances, which is to say when the goal was to protect the army from missiles, and not to immediately carry the fight to the enemy.

I'll admit that I exaggerated their response, but I'd think a fully supported Roman legion would have an easier time of it compared to a rival Iceni tribe. If all else fails, they could build their own fortifications around the fort, ala the Battle of Alesia, making any sally by the defenders a strange sort of counter siege.
The Romans were clearly perfectly capable of breaking a hill-fort, since they did it. I never denied that, merely that it was a laughable obstacle rendered obsolete by siege engines.