Like the inter-Feuding tribes of Gaul and Britton,
Caledonian clans also discovered what it meant
to face organized and disciplined forces of Rome.

Like Vercingetorix vs. Caesar in Gaul , they couldn't
just slap together a range of rival tribes and expect
to get it over the Romans with sheer numbers .. also
by this time military reforms by Marius and Augustus
had made the army better than ever.... Gone was the
levy/conscript system...
Soldiers were now full-time career, drawn only from
volunteers, with standardized equipment and training.

Augustus had also much improved the logistics of
supply.. No longer was the army as restricted [as
Caesar was] regarding essential grain, or as bound
to the limits of seasonal warfare (ie) a bad season
of grain in Gaul, or a campaign delayed through
neccesity because crops were not ready, or a
campaign in Germania where Germanics were
not much into agriculture, hampered movements
and the decisions Caesar could make.


-Bulletproof and Waterproof don't mean Idiotproof.