He was a lawful prince, and he acted on the maxims of an usurper.

Having made it a rule never to remove far from the capital, and jealous of every reputation which seemed too great for the measure of a subject, he neither undertook any enterprise of moment in his own person nor cared to commit the conduct of it to another.

There was little in a British triumph that could affect a temper like that of Tiberius.
His successor, Caligula, was not influenced by this, nor indeed by any regular system; for, having undertaken an expedition to Britain without any determinate view, he abandoned it on the point of execution without reason.

And adding ridicule to his disgrace, his soldiers returned to Rome loaded with shells.

These spoils he displayed as the ornaments of a triumph which he celebrated over the Ocean,--if in all these particulars we may trust to the historians of that time, who relate things almost incredible of the folly of their masters and the patience of the Roman people.
But the Roman people, however degenerate, still retained much of their martial spirit; and as the Emperors held their power almost entirely by the affection of the soldiery, they found themselves often obliged to such enterprises as might prove them no improper heads of a military constitution.