Franklin's vision of an expanding British North American empire required a colonial union. The lesson, Franklin learned from the example of the Six Nations Confederacy was about the importance of union to the establishment of the imperial control of North America. The most radical aspect of Franklin's vision was his conception of an emerging parity between England and the colonies. Washington's and Franklin's efforts to spur unity suggest that the move toward the creation of an American union is best understood as a 'grasstips' movement. Franklin and Washington's participation in the expansionist thrust reflected both the personal and the public interests each had in acquiring control of the Ohio Country. The revolutionary faction in the colonies wouldn't accept political subordination or limitations on its territorial and commercial expansionism. The bloody battles at Lexington and Concord in April 1775 marked the beginning of a de facto war of independence for the colonies.