Wall Mile 24 [HB 186–7]
It is time to leave the south side of the Military Road and the gently undulating remains of the Vallum. We climb up to a stile and have to cross the Military Road. Once more, care is essential, given the breakneck speed at which motorists hurtle along here; there are signs warning them of pedestrians crossing, but you will not see many decelerate as a result.
We are now on the north lip of the ditch, following the upcast mound or counterscarp. Archaeologists, bless ’em, get confused over these terms (they tend to be used interchangeably), but suffice it to say that the counterscarp is a part of the upcast mound, but they are not synonymous (the former is that part of the latter facing the ditch; clear? I may test you later).
To our left, beyond the ditch, the characteristic form of the roadside walls along the Military Road, built at the same time by the contractors, also using Wall stone, has two rows of through-stones, but this detail is not usually copied in subsequent repairs to the walls. These walls are interesting in their own right (as indeed is the Military Road, about which we shall say more in due course). Before the road was built, the remnants of Hadrian’s Wall itself was the major land division, so destroying it and laying a road required that walls be built on either side of it, to placate the landowners. Therefore, the road-laying gangs also had to undertake wall construction, and there are still some fine examples of the drystone-wallers’ art to be seen as we progress towards our destination.
Further to the south, unseen by us, the Vallum switches between an earthwork in pasture and cropmarks in standing crops and then, after a while, back again, just in time for a change of course. As we reach the realignment, a field wall swoops across the ditch, highlighting its profile.
That change in the alignment of the course of the Wall (it has been on a slightly more northerly heading from the point where the Dere Street crosses it at the Portgate roundabout) sees it shift to almost due east to west until we reach Heavenfield. At this slight angle, the ditch ploughs through an outcrop (almost as if it had been deliberately aimed at it), exploiting a little trick used by the ditch-diggers with which we shall become familiar: it is dug into the foreslope. Doing this forced an enemy to run uphill to reach the obstacle (a task made more difficult by the upcast mound), whilst the use of the foreslope enhanced the south face of the ditch, which confronted an attacker trying to get across it.
Next to us, the ditch often shows signs of moisture, with damp-loving plant species like Juncus and even standing water within it in places. The land along here continues to slope gently from south to north, enhancing the effect of the ditch and counterscarp.
Milecastle 25 (Codlawhill) [HB 187; haiku]
Although it survives as an earthwork, there is nothing for us to see as it is on the far side of the Military Road and well out of our reach or sight. Like its neighbours on either side, it is a long-axis milecastle and was excavated in 1930.