During the Kościuszko Uprising in 1795, Niemcewicz served as aide to Tadeusz Kościuszko. Both were captured by the Russians at the Battle of Maciejowice in 1794 and imprisoned in the Peter and Paul Fortress at St. Petersburg along with Niemcewicz's aide-de-camp named Kuźniewski. In 1796, on the death of Tsaritsa Catherine the Great, they were released by Tsar Paul I and made their way together to the United States. They sailed on the ship "Adriana" from Bristol, in England, in the company of the Portuguese abbot and botanist, José Correia da Serra, who served as the chaplain on ship for Niemcewicz and Kościuszko. They arrived in Philadelphia on August 18, 1797. During his stay, he visited Niagara Falls. In 1798, he was elected a member of the American Philosophical Society.