intervention at the
proper time.

An invasion, to be successful, must, be proportioned in magnitude to the
end to be attained and to the obstacles to be overcome.

An invasion against an exasperated people, ready for all sacrifices and
likely to be aided by a powerful neighbor, is a dangerous enterprise, as
was well proved by the war in Spain, (1808,) and by the wars of the
Revolution in 1792, 1793, and 1794. In these latter wars, if France was
better prepared than Spain, she had no powerful ally, and she was
attacked by all Europe upon both land and sea.

Although the circumstances were different, the Russian invasion of
Turkey developed, in some respects, the same symptoms of national
resistance. The religious hatred of the Ottoman powerfully incited him
to arms; but the same motive was powerless among the Greeks, who were
twice as numerous as the Turks. Had the interests of the Greeks and
Turks been harmonized, as were those of Alsace with France, the united
people would have been stronger, but they would have lacked the element
of religious fanaticism. The war of 1828 proved that Turkey was
formidable only upon the frontiers, where her bravest troops were found,
while in the interior all was weakness.

When an invasion of a neighboring territory has nothing to fear from the
inhabitants, the principles of strategy shape its course. The popular
feeling rendered the invasions of Italy, Austria, and Prussia so prompt.
(These military points are treated of in Article XXIX.) But when the
invasion is distant and extensive territories intervene, its success
will depend more upon diplomacy than upon strategy. The first step to
insure success will be to secure the sincere and devoted alliance of a
state adjoining the enemy, which will afford reinforcements of troops,
and, what is still more important, give a secure base of operations,
depots of supplies, and a safe refuge in case of disaster. The ally must
have the same interest in success as the invaders, to render all this
possible.

Diplomacy, while almost decisive in distant expeditions, is not
powerless in adjacent invasions; for here a hostile intervention may
arrest the most brilliant successes. The invasions of Austria in 1805
and 1809 might have ended differently if Prussia had interfered. The
invasion of the North of Germany in 1807 was, so to speak, permitted by
Austria. That of Rumelia in 1829 might have ended in disaster, had not a
wise statesmanship by neg