Several times in the century and a half of their existence, when the colonies found themselves threatened by their enemies, they had united, or at least made an effort to unite, for mutual help.

The New England Confederation of 1643 was organized primarily for protection against the Indians and incidentally against the Dutch and French.

Whenever trouble threatened with any of the European powers or with the Indians--and that was frequently--a plan would be broached for getting the colonies to combine their efforts, sometimes for the immediate necessity and sometimes for a broader purpose.

The best known of these plans was that presented to the Albany Congress of 1754, which had been called to make effective preparation for the inevitable struggle with the French and Indians.

The beginning of the troubles which culminated in the final breach with Great Britain had quickly brought united action in the form of the Stamp Act Congress of 1765, in the Committees of Correspondence, and then in the Continental Congress.
It was not merely that the leaven of the Revolution was already working to bring about the freer interchange of ideas; instinct and experience led the colonies to united action.