He was now thoroughly on the alert, and actively opposed at all points the schemes of those whom he regarded as concerned in or instigating the intrigue. He commented harshly on Tyler's annual message, which made a strong plea for annexation, even at the cost of a war both with Great Britain and Mexico; also on Calhoun's letter to Lord Aberdeen, which was certainly a remarkable diplomatic document,--being a thesis on slavery and the benefits resulting from it. Tyler's object was to prepare the way for a secret treaty, which should secure the desired object. Benton, in the course of some severe strictures on his acts, said, very truly, that it was evidently the intention to keep the whole matter as secret as possible until the treaty was concluded, "and then to force its adoption for the purpose of increasing the area of slave territory, or to make its rejection a cause for the secession of the Southern States; and in either event and in all cases to make the question of annexation a controlling one in the nomination of presidential candidates, and also in the election itself." When the treaty proposed by the administration was rejected, and when it became evident that neither Tyler nor Calhoun, the two most prominent champions of the extreme separatists, had any chance for the Democratic nomination, the disunion side of the intrigue was brought to the front in many of the Southern States, beginning of course with South Carolina. A movement was made for a convention of the Southern States, to be held in the interest of the scheme; the key-note being struck in the cry of "Texas or disunion!" But this convention was given up, on account of the strong opposition it excited in the so-called "Border States,"--an opposition largely stirred up and led by Benton. Once more the haughty slave leaders of the Southeast had found that in the Missouri Senator they had an opponent whose fearlessness quite equaled their own, and whose stubborn temper and strength of purpose made him at least a match for themselves, in spite of all their dash and fiery impetuosity. It must have sounded strange, indeed, to Northern ears, accustomed to the harsh railings and insolent threats of the South Carolina senators, to hear one of the latter complaining that Benton's tone in the debate was arrogant, overbearing, and dictatorial towards those who were opposed to him. This same Senator, McDuffie, had been speaking of the proposed Southern meeting at Nashville; and Benton warned him that such a meeting would never take place, and that he had mistaken the temper of the Tennesseans; and also reminded him that General Jackson was still alive, and that the South Carolinians in particular must needs be careful if they hoped to agree with his followers, whose name was still legion, because he would certainly take the same position towards a disunion movement in the interests of slavery that he had already taken towards a nullification movement in the interests of free trade.