Mackenzie wanted Canadians to lead the next invasion but still receive American assistance. When Van Rensselaer attempted an invasion of Kingston from Hickory Island, Mackenzie refused to participate, citing a lack of confidence in the mission's success. Patriot forces near Detroit attempted to invade Upper Canada but were repelled by British forces. Mackenzie stopped recruiting for the Patriots to avoid ridicule. Years in the United States (1838–1849) Support for Patriots and Mackenzie's Gazette Mackenzie and his wife arrived in New York City and launched Mackenzie's Gazette on May 12, 1838, after soliciting subscriptions from friends. Its early editions supported the Patriots and focused on Canadian topics, but pivoted to American politics in August 1838. He suspended publication of his paper in the fall of 1838 and moved to Rochester to rebuild the Patriot forces by creating the Canadian Association. The association struggled to attract Canadian members and unsuccessfully fundraised for Mackenzie to publish an account of the Upper Canada Rebellion. The money was reallocated to Mackenzie's defence fund for his upcoming trial. He restarted Mackenzie's Gazette in Rochester on February 23, 1839. Neutrality law trial The trial for Mackenzie's violation of American neutrality laws began on June 19, 1839; he represented himself in the proceedings. The district attorney argued that Mackenzie recruited members, established an army, and stole weapons for an invasion. Mackenzie contended that Britain and the United States were at war because the British destroyed an American ship in the Caroline affair and the Neutrality Act did not apply. Mackenzie wanted to submit evidence that the Upper Canadian Rebellion was a civil war, as a person cannot be convicted of violating the Neutrality Act if the country is engaged in a civil war. The judge refused to allow this evidence because, according to American law, only the United States Congress can declare if a country is in a civil war, which they did not do. Mackenzie was frustrated and did not call further witnesses. The judge sentenced Mackenzie to eighteen months in jail and a $10 () fine. Mackenzie did not appeal the ruling after consulting with lawyers. He said after the trial that he was depending upon key witnesses to give testimony, but they did not come to the courtroom. He also denounced the application of neutrality laws, wrongly stating the law had not been applied for nearly fifty years. Imprisonment Mackenzie was imprisoned on June 21,