The dispute quickly grew from bad to worse, and in 1773 officers sent to New England were resisted in the performance of their duty. To such a pass did matters now speedily come that in 1775 Franklin decided, as well from patriotic motives as from a regard to his personal safety, to return to America. He was immediately elected a delegate to the congress convened by the thirteen provinces or states to concert measures for their common defence, and which at once declared in favour of dissolving the political connection with Great Britain.

Franklin soon became one of the most active men in the contest between England and the Colonies, which resulted in the declaration of independence, July 4, 1776, and in the establishment of what has since been known as the Republic of the United States. Towards the end of 1776 he was sent as special envoy to France to negotiate a treaty of alliance. His fame as a philosopher and statesman had already preceded him, and he was received with every mark of consideration and respect. His mission to France was successful, and in February, 1778, he signed a treaty of alliance, offensive and defensive, between France and the United States. This produced war between England and France, which lasted for several years. However, in September, 1783, the British government recognized the independence of the United States, and Franklin signed the treaty of peace between the mother country and her revolted colonies.

He continued to discharge the duties of minister plenipotentiary to France until 1785, when, in consequence of his advancing age and infirmities, he was relieved of the post at his own request. Reaching Philadelphia in September of that year, he was elected almost immediately president of the State of Pennsylvania. To this office he was twice unanimously re-elected.