The American colonies broke with the British empire in 1776, but could they remain united even as they fought in a common cause? The people in the colonies had profound differences—religious, social, political and economic—that surfaced in local communities as well as in Congress and the Continental Army. Colonists’ resistance to Great Britain magnified these differences, especially as more Americans began to question the institution of slavery in light of new ideals of liberty. Yet, these colonists were able not only to join in a common effort but to create a political system which has united Americans, despite their differences, for more than two centuries. In the 2017 George Rogers Clark Lecture, Professor Robert Allison describes the diversity of the North American British colonists and how American patriots from various backgrounds were able to unite in a common cause for independence.