st of the Rio
Grande. But in a sparsely settled country, where water is not
abundant, the actual border line, if there be any clear line, between
settlement from one side and settlement from the other will not for the
convenience of treaty-makers run along a river, but rather for the
convenience of the settlers along the water-parting between two rivers.
So Mexico claimed both banks of the Rio Grande and Spanish settlers
inhabited both sides. Polk ordered General Zachary Taylor, who was
allowed no discretion in the matter, to march troops right up to the
Rio Grande and occupy a position commanding the encampment of the
Mexican soldiers there. The Mexican commander, thus threatened,
attacked. The Mexicans had thus begun the war. Polk could thus allege
his duty to prosecute it. When the whole transaction was afterwards
assailed his critics might be tempted to go, or represented as going,
upon the false ground that only Congress can constitutionally declare
war--that is, of course, sanction purely offensive operations. Long,
however, before the dispute could come to a head, the brilliant
successes of General Taylor and still more of General Scott, with a few
trained troops against large undisciplined numbers, put all criticism
at a disadvantage. The City of Mexico was occupied by Scott in
September, 1847, and peace, with the cession of the vast domain that
had been coveted, was concluded in May, 1848.

War having begun, the line of the Whig opposition was to vote supplies
and protest as best they might against the language endorsing Polk's
policy which, in the pettiest spirit of political manoeuvre, was
sometimes incorporated in the votes. In this Lincoln steadily
supported them. One of his only two speeches of any length in Congress
was made on the occasion of a vote of this kind in 1848. The subject
was by that time so stale that his speech could hardly make much
impression, but it appears to-day an extraordinarily clear, strong,
upright presentment of the complex and unpopular case against the war.
His other long speech is elevated above buffoonery by a brief, cogent,
and earnest passage on the same theme, but it was a frank piece of
clowning on a licensed occasion. It was the fashion for the House when
its own dissolution and a Presidential election were both imminent to
have a sort of rhetorical scrimmage in which members on both sides
spoke for the edification of their own constituencies and that of
Bunc