For arms are of little value in the field unless there is wise counsel at home.

[Parvi enim sunt foris arma, nisi est consilium domi.]

Marcus Tullius Cicero (106-43 BC) Roman orator, statesman, philosopher

De Officiis [On Duties; On Moral Duty; The Offices], Book 1, ch. 22 (1.22) / sec. 76 (44 BC) [tr. Miller (1913)]
    (Source)

Peabody comments, "A verse, quoted probably from some lost comedy, the measure being one employed by the comic poets." None of the other translators call this out or show the text as separate except Peabody.

(Source (Latin)). Alternate translations:

For armies can signify but little abroad, unless there be counsel and wise management at home.
[tr. Cockman (1699)]

Armies abroad avail little, unless there be wisdom at home.
[tr. McCartney (1798)]

An army abroad is but of small service unless there be a wise administration at home.
[tr. Edmonds (1865)]

Valor abroad is naught, unless at home be wisdom.
[tr. Peabody (1883)]

An army in the field is nothing without wisdom at home.
[tr. Gardiner (1899)]

For weapons have small value abroad unless there is good advice at home.
[tr. Edinger (1974)]