The Sons of Liberty was a group formed in the American colonies to protest the levying of new taxes on the colonies by Britain in the aftermath of the French and Indian War, which had cost the "Mother Country" across the pond quite a bit of money defending these same colonies. Initially, the Sons of Liberty reiterated that their issue with Britain was the levying of taxes without colonial representation, and that despite this protest, they remained subjects loyal to the Crown. That civility was soon a thing of the past, however, when in response to the Stamp Act tax of 1765, a tax collector for the state of Massachusetts, Andrew Oliver, was hung in effigy on what is now Boston's fashionable Newbury Street. The Sons group continued the violence on into the night, burning Oliver's property, stoning and then burning his home, and finally, what was left of his effigy.
Interestingly, John Adams and his cousin Samuel Adams, both figures heavily involved in the controversy with Britain, never joined the Sons of Liberty for fear of being associated with the violence of the group that became the rule rather than the exception over time. Before all was said and done, the Sons of Liberty were responsible for what is called the Boston Tea Party, a massive 1773 destruction of crates of tea sitting in Boston Harbor on British ships, plus less known acts such as the burning of the HMS Gaspee in 1772.
This was the backdrop against which Forbes set her coming-of-age story of the selfish, temperamental, arrogant kid who grew into a responsible young man who learned to value something larger than himself and his immediate wishes and desires.