ull exposition of my right to the province.
The same day my ambassador was received in Vienna, I entered Silesia
with my army!"[94]

Such would be a prompt and impulsive answer to the manifold
prevarications of seditious Mexico. But the army we advanced and the
country we occupied, were neither the army of Frederick nor the pleasant
vales of rich and populous Silesia. A nearly desolate waste, stretched
from the Nueces to the Rio Grande, barren alike in soil and inhabitants,
and tempting none to its dreary wilderness but nomadic _rancheros_ or
outlaws who found even Mexico no place of refuge for their wickedness.
It was, surely, not a land worthy of bloodshed, and yet, in consequence
of its sterility, it became of vast importance on a frontier across
whose wide extent enemies might pass unobserved and unmolested. With the
entire command of the Rio Grande from its source to its mouth in the
hands of our enemy, and the whole of this arid region flanking the
stream and interposing itself between Mexico and our troops, it is
evident that our adversaries would possess unusual advantages over us
either for offensive or defensive war. The mere control of the
embouchure of the river was no trivial superiority, for, on a stormy and
inhospitable coast, it was almost impossible to support an effectual
blockade and thus prevent the enemy from being succored along his whole
frontier with arms and provisions from abroad. By seizing, however, the
usual points of transit and entrance on the lower Rio Grande many of
these evils might be avoided; and, if Mexico ultimately resolved on
hostilities, we should be enabled to throw our forces promptly across
the river, and by rapid marches obtain the command of all the military
positions of vantage along her north-eastern boundary.

The foresight of Frederick the Great disclosed to him the military value
of Silesia in the event of a war with Austria, and it was probably that
circumstance, quite as much as his alleged political rights, that
induced him to enter it with an army on the day when he commenced
negotiations. He began the war with Austria by surprising Saxony, and,
during all his difficulties, clung tenaciously to the possession of
Silesia. Saxony was important as a military barrier covering Prussia on
the side of Austria, while Silesia indented deeply the line of the
Austrian frontier and flanked a large part of Bohemia.[95] Thus Saxony
and Silesia formed a natural fortification for