Suchorzewski, with several other opponents of the constitution, departed to Saint Petersburg in the Russian Empire, where he became one of the founding members and high-ranking officials ("konsyliarz") of the Confederation of Targowica. Derdej speculated that out of all those who signed the act of the Confederation, Suchorzewski was the only one who might have thought they were really acting in the country's best interest. He commanded a cavalry brigade in the Confederation forces during the War in Defense of the Constitution that the Confederates eventually won, overthrowing the Constitution. During the Kościuszko Insurrection he was sentenced, "in absentia", to a death by hanging, eternal infamy, loss of all titles and confiscation of possessions. His effigy was hanged on the 29 September 1794.