Very hot day. I’ve spent much of it dozing. I didn’t even manage to go and grab a drink outside some pub.
And I got thinking about hill forts again. There’s a very big one not far from where I live, in the Malvern Hills, called British Camp. By some accounts, it’s where Caractacus made his last stand against the Romans in 51 AD.
The series of ramparts would clearly seem to be defensive in nature, with defenders retreating uphill from one line to the next as the lowest ones were overrun. But I also thought today that they might also have served to collect rainwater, if there was no natural spring.
But the more I think about it, the more I think that the defenders wouldn’t have just waited for attackers to climb the slopes to the ramparts, but would have rolled rocks down the lower slopes (just above the road in the photo) onto them as they advanced up the slopes.
They would have only been able to do this on hills that were steep enough to ensure that stones rolled down them gathered speed, rather than came to a stop.
They would have had to make sure that the lower slopes were free from obstructions to such rocks. They would have had to clear away all boulders, hillocks, trees, bushes, etc, to ensure that stones rolled down the slopes weren’t stopped or deflected.
It would also have meant that they would have wanted to ensure that the rocks stayed near the ground, and didn’t bounce off the ground over the heads of the advancing attackers, by ensuring that they were as round as possible.
And probably these rounded stones – pebbles of a kind that can be found on many beaches – could be quite small. With lots of small stones, they could be much more certain of hitting attackers than with a few large stones. And assuming that the stones rolled down the slopes gathered speed, and their kinetic energy, ½.m.v², was what determined their impact, they’d have used small stones when the attackers were at the bottom of the slopes, and larger ones as the attackers advanced up the slope, keeping the very largest for when they were near the top.
This would have meant that they would have had to keep huge piles of stones up on the ramparts, and lots of baskets to carry them to the ramparts and empty them down the slopes. Both women and children could have assisted in emptying baskets of stones down the slopes.
The defenders would have probably had plenty of practice trying to hit targets at the bottom of the hill. They probably held regular competitions in peacetime.
They might also have had circular millstones with wooden axles through their centres, which they would spin up on cradles before releasing them. These ‘secret weapons’ would have much greater kinetic energy, and greater range. They might also have been able to be more accurately aimed.
All in all, it was probably next to impossible to capture these hill forts by advancing up their slopes. You’d be facing something like a continuous avalanche of stones rolling and bouncing down the slope at every step, with the stones getting bigger the further up them you got.
The Romans probably stayed out of range of these avalanches of stones, and used their ballista to fire stones and flaming arrows up at the thatched cottages at the top of the ramparts. A Roman ballista had a range of about 500 m, and since the top of British Camp is 100 m above the lake at its foot, the Roman engineers could probably usually manage to find a spot where the entire fort was in range of their ballista, but out of range of the defender’s rocks. And once they’d reduced one hill fort, they’d collect up the stones and arrows they’d used, and re-use them on the next hill fort.