Lincoln’s position on the Mexican War has been generally approved by the moral sense of the country; but it gave his political enemies an opportunity, which they were not slow to improve, for trying to make political capital out of it and using it to create a prejudice against him.  Douglas in particular never missed an opportunity of referring to it.  In the great joint debate in 1858 he spoke of Lincoln’s having “distinguished himself in Congress by his opposition to the Mexican War, taking the side of the common enemy against his own country.”  No better refutation of these oft-repeated charges could be made than that given by Lincoln himself on this occasion.  “The Judge charges me,” he said, “with having, while in Congress, opposed our soldiers who were fighting in the Mexican War.  I will tell you what he can prove by referring to the record.  You remember I was an old Whig; and whenever the Democratic party tried to get me to vote that the war had been righteously begun by the President, I would not do it.  But whenever they asked for any money or land-warrants, or anything to pay the soldiers, I gave the same vote that Judge Douglas did.  Such is the truth, and the Judge has a right to make all he can out of it.”

The most ambitious utterance of Lincoln during this term in Congress was that of July 27, 1848, when he took for his subject the very comprehensive one of “The Presidency and General Politics.”  It was a piece of sound and forcible argumentation, relieved by strong and effective imagery and quiet humor.  A considerable portion of it was occupied with an exposure of the weaknesses of General Cass, the Presidential candidate opposed to General Taylor.  Lincoln ridiculed Cass with all the wit at his command.  An extract from this speech has already been quoted in this work, in the account of Lincoln in the Black Hawk War.  Another passage, equally telling, relates to the vacillating action of General Cass on the Wilmot Proviso.  After citing a number of facts in reference to the case, Lincoln says:  “These extracts show that in 1846 General Cass was for the Proviso at once; that in March, 1847, he was still for it, but not just then; and that in December, 1847, he was against it altogether.  This is a true index to the whole man.  When the question was raised, in 1846, he was in a blustering hurry to take ground for it.  He sought to be in advance, and to avoid the uninteresting position of a mere follower.  But soon he began to see glimpses of the great Democratic ox-gad waving in his face, and to hear indistinctly a voice saying, ‘Back!  Back, sir!  Back a little!’ He shakes his head and bats his eyes and blunders back to his position of March, 1847.  But still the gad waves, and the voice grows more distinct and sharper still, ‘Back, sir!  Back, I say!  Further back!’ And back he goes to the position of December, 1847, at which the gad is still and the voice soothingly says, ‘So!  Stand still at that!’”