.. merely pointing out that Ireland was as about as potentially lucrative to
an invader as anywhere else.
In regards to Roman Empire conquests that
is simply not true, since more wealthy and
established regions of the empire payed for
expensive campaigns into other areas with
little or no real financial reward or a net loss
for the coffers of Rome.
Hadrian drew the line at the Rhine and Tiberius allowed Germanicus
a few campaigns over the Rhine, but finally said no more due to there
being no gains for Rome...seems the efforts of Germanicus were
more about avenging Varus/ lost legions of 9 A.D.
and having destroyed Arminius forces and razed
everything German for 50 miles around and recovering
two legionary standards, it seems his task was accomplished.
Also the driving forces/agendas for Roman campaigns
were different in the Republic with personally competitive
Triumvirate arrangements (like Caesar, Pompey and Crassus)
vs the new Imperial system under an Emperor.
Caesar briefly invaded Britannia twice for his own
reasons (and he operated in Gaul for a combination
of his own reasons and the requirement of the senate
to defend Gallic allies).. but left Britannia behind cause
he had higher priorities in Gaul.
EARLIER in the piece, Rome was not much interested in
the bulk of Gaul, but got involved to protect its land trade
routes to colonies in Iberia, which were being threatened
by Gauls that were raiding Greek trading posts...
And together with the fact Rome had an allied
contract with the Greeks, so came to their defence.
After that, ambitious Republic Romans saw military
campaigns in Gaul, Germania and Britannia as means
of advancing their political careers.
The Roman people loved and celebrated winners..
when Caesar defeated Vercingetorix at Alesia,
Roman senate declared 20 days of thanksgiving.
Even when Caesar crossed the Rhine for only
18 days to burn down villages and destroy food
stores of Germanic tribes and not really engage in combat,
(since Germanics fled and hid in the forest)
He still got a great reception in Rome for his
Pioneering efforts..