As nearly everyone knows, the Romans legions while on march knocked off early enough in the afternoon to build a protective fort which included trenching outside of a palisade. Every tent and headquarters was erected in the same plan every day so soldiers knew exactly where they were in the encampment, even at night.
It was a routine that stood them in good stead over the years.
Every day, when the legion moved, a new fort was created at the best defensible site. So remains of an older route march fort location under the site of a later permanent fort probably wouldn’t be unusual
Comes in handy for those late night dashes to the trench. :-))
:’) One of the forts could easily be from Vespasian’s campaign in Britain, although having said that it occurs to me that I’m not sure how far west he went. He’s definitely the general who made the big move in the conquest of most of Britain, reducing the oppida with artillery (not gunpowder obviously, so nobody reading this write in, okay?) which was his main specialty. If there had been an orderly system of succession (and retirement from the supreme office by means other than death) it’s basically assumed IMO that the Romans would have finished up in Caledonia, and they apparently had a forward base in Ireland (there’s a topic in the FRchives about that). Thanks wildbill!