Federalist Papers 4E

One government can collect and avail itself of the talents and experience of the ablest men, in whatever part of the Union they may be found. It can move on uniform principles of policy. It can harmonize, assimilate, and protect the several parts and members, and extend the benefit of its foresight and precautions to each. In the formation of treaties, it will regard the interest of the whole, and the particular interests of the parts as connected with that of the whole. It can apply the resources and power of the whole to the defense of any particular part, and that more easily and expeditiously than State governments or separate confederacies can possibly do, for want of concert and unity of system. It can place the militia under one plan of discipline, and, by putting their officers in a proper line of subordination to the Chief Magistrate, will, as it were, consolidate them into one corps, and thereby render them more efficient than if divided into thirteen or into three or four distinct independent companies.

What would the militia of Britain be if the English militia obeyed the government of England, if the Scotch militia obeyed the government of Scotland, and if the Welsh militia obeyed the government of Wales? Suppose an invasion; would those three governments (if they agreed at all) be able, with all their respective forces, to operate against the enemy so effectually as the single government of Great Britain would?