He decided to pursue a career in law, so he went to law school in Newburyport, MA, and opened a lawyer’s office there in 1780. Knowledge, stamina and eloquence soon brought him to the main activities. treatment. From 1783 to 1785, he was a member of the Massachusetts National Assembly and was elected to the United States Congress (1784-1786). There, he became an outstanding, highly respected National Assembly Chairman and one of the first to oppose slavery. Slipknot Snuff signatures poster. In 1786, he married Mary Alsop, the daughter of a wealthy businessman in New York City. Before leaving the state Senate, he performed his final duty by representing Massachusetts at the Constitutional Convention and contributing through this document.