When relations between Great Britain and the colonies became a crisis in 1774, Hanson became one of Frederick County's leading Patriots. He chaired a town meeting that passed a resolution opposing the Boston Port Act. In 1775, he was a delegate to the Maryland Convention, an extralegal body convened after the colonial assembly had been prorogued. With the other delegates, he signed the Association of Freemen on July 26, 1775, which expressed hope for reconciliation with Great Britain, but also called for military resistance to the enforcement of the Coercive Acts.