He served as quartermaster general of the New York Militia during the American Civil War. Following the war, he devoted more time to New York Republican politics and quickly rose in Senator Roscoe Conkling's political organization. President Ulysses S. Grant appointed him to the post of Collector of the Port of New York in 1871, and he was an important supporter of Conkling and the Stalwart faction of the Republican Party. In 1878, President Rutherford B. Hayes fired Arthur as part of a plan to reform the federal patronage system in New York. Eastern newspapers praised the veto, while it was condemned in the Western states. Congress was unable to override the veto, but passed a new bill reducing the immigration ban to ten years.