In Federalist No. 16, Hamilton continues his discussion of the insufficiency of the present confederation to preserve the union.
In this essay, Hamilton begins by noting that it has been seen that
delinquencies in the members of the Union are its natural and necessary offspring; and that whenever they happen, the only
constitutional remedy is force, and the immediate effect of the use of it, civil war. Truer words could not have been said as History served to prove Hamilton right (with the civil wars that would still erupt until the Union was complete and in agreement on core principles).
Furthermore, if there should not be a large army constantly at the disposal of the national government it would either not be able to
employ force at all, or, when this could be done, it would amount to a war between parts of the Confederacy concerning the
infractions of a league, in which the strongest combination would be most likely to prevail, whether it consisted of those who
supported or of those who resisted the general authority. In other words, while civil war could occur within a Union, the potential for civil war is much higher between a loose conglomeration of confederacies.
In addition, where military is concerned, even in those confederacies which have been composed of members smaller than many of our counties, the principle of
legislation for sovereign States, supported by military coercion, has never been found effectual. Plus, it has rarely been attempted
to be employed, but against the weaker members; and in most instances attempts to coerce the refractory and disobedient
have been the signals of bloody wars, in which one half of the confederacy has displayed its banners against the other half.
So, if we want to minimize the chances of civil war, a Union is much better than a loose collection of confederacies, especially when the Union stands as one.