The Copperheads were a prominent faction of northern US Democratic Party members that existed from 1860 to 1868, opposing war with the South. The Copperheads were led by Clement Vallandigham and Alexander Long, and the Copperheads opposed the modernization reforms passed by the US Republican Party, favoring Andrew Jackson's conservative form of democracy. The Copperheads gained support during times of crisis for the Union, especially after disastrous battles such as Bull Run in 1861, Fredericksburg in 1862, and Chancellorsville in 1863, but the victories of 1864 would lead to Copperhead power diminishing.