was astonished by his presence. Nine of the most considerable princes
repaired to his camp, and fell prostrate at his feet. Such a treaty was
humbly received by the Germans, as it pleased the conqueror to dictate.
He exacted a strict restitution of the effects and captives which they
had carried away from the provinces; and obliged their own magistrates
to punish the more obstinate robbers who presumed to detain any part of
the spoil. A considerable tribute of corn, cattle, and horses, the only
wealth of barbarians, was reserved for the use of the garrisons which
Probus established on the limits of their territory. He even entertained
some thoughts of compelling the Germans to relinquish the exercise of
arms, and to trust their differences to the justice, their safety to
the power, of Rome. To accomplish these salutary ends, the constant
residence of an Imperial governor, supported by a numerous army, was
indispensably requisite. Probus therefore judged it more expedient to
defer the execution of so great a design; which was indeed rather of
specious than solid utility. [40] Had Germany been reduced into the state
of a province, the Romans, with immense labor and expense, would have
acquired only a more extensive boundary to defend against the fiercer
and more active barbarians of Scythia.

[Footnote 40: Hist. August. 238, 239. Vopiscus quotes a letter from
the emperor to the senate, in which he mentions his design of reducing
Germany into a province.]

Instead of reducing the warlike natives of Germany to the condition of
subjects, Probus contented himself with the humble expedient of raising
a bulwark against their inroads. The country which now forms the circle
of Swabia had been left desert in the age of Augustus by the emigration
of its ancient inhabitants. [41] The fertility of the soil soon attracted
a new colony from the adjacent provinces of Gaul. Crowds of adventurers,
of a roving temper and of desperate fortunes, occupied the doubtful
possession, and acknowledged, by the payment of tithes the majesty
of the empire. [42] To protect these new subjects, a line of frontier
garrisons was gradually extended from the Rhine to the Danube. About the
reign of Hadrian, when that mode of defence began to be practised, these
garrisons were connected and covered by a strong intrenchment of trees
and palisades. In the place of so rude a bulwark, the emperor Probus
constructed a stone wall of a considerable height, and stren