What Was Hadrian's Wall For?

Historically, it was self evident what hadrian's wall was for. It was a defensive barrier er. They didn't really question thatd even actually in the elizabethan period,. There was a plan to build a new border wall between england and scotland reduce border reaving. Soi i's clearly seen as a defensive barrier. What happens though is that the mile castles are discovered. These kinds of what we would call a fortlet. And so once it was realized that they could be found regularly every mile, which is why they're called mile castles, made people start to wonder, well, wait, tha's that's not particularly defensive. If you can