Originally Posted by Gus


but if the legion was strong enough, had enough slaves and supplies they'd have pushed to the far north end.

but they didn't do that. they set up a defensive perimeter and dug in...


It was about priorities, Caledonia didn't have a lot to offer
for all the cost and effort.
Gen. Gnaeus Julius Agricola campaigned in Caledonia
for years (76-84 AD) and got good results in the battle
of Mons Grapius.. He built a series of settlements and
fortifications.

[Linked Image from i.postimg.cc]

Romans built the Antonine and Hadrians but
they didn't just dig in and statically defend the
walls..They conducted punitive actions northward
as required.
Septimus Severus campaigned North (208-211 AD)
in a major offensive but the barbarians were not
willing to engage. [campaign cut short by illness
and death of Septimus Severus] .
The Romans also conducted punitive actions to the
South of those walls..They were strategic structures
defining the boundary of the empire, not a line where
troubles ended]] ...They withdrew the boundary to
Hadrians to better consolidate, as it was more
practically manageable.

Here you can see how forts dotted both sides:

[Linked Image from i.postimg.cc]

-Bulletproof and Waterproof don't mean Idiotproof.