Such was the nature of American republican liberty; not then fully understood, not then fully developed in all the States, but yet discovered,--a liberty more difficult of attainment, more elaborate in its structure, and therefore more needful of defence, than any of the other forms of constitutional freedom under which civilized man had hitherto been found. Now, the fate of republican liberty in America, at that day, depended directly upon the preservation of some union of the States, and not simply upon the existing State institutions, or upon the desires of the people of each separate State. It is true, that their previous training and history, and their own intelligent choice, had made the States, in all their forms and principles, republican governments; and almost all of them had, at this period, written constitutions, in which the American ideal of such governments was aimed at, and more or less nearly reached. But how long were these constitutions, these republican forms, to exist? What was to secure them? Who was to stand as their guarantor and protector, and to vindicate the right of the majority to govern and alter and modify? Who was to enforce the rules which the people of a State had prescribed for their own action, when threatened by an insurgent and powerful minority? Who was to protect them against foreign invasion or domestic violence? There was no common sovereign, or supreme arbiter, to whom they could all alike appeal. There was no power upon this broad continent to whom the States could intrust the duty of preserving their institutions inviolate, except the people of the United States in some united and sovereign capacity. No single State, however great its territory or its population, could have discharged these duties for itself by its unaided power; for no one of them could have repelled a foreign invasion alone, and the government of one of the most respectable and oldest of them, whose people had exhibited as much energy as any other community in America, had almost succumbed to the first internal disorder which it had been forced to encounter.