John Thomas, founder of the Christadelphians, was also a British emigrant who had been associated with the Campbellite movement in Illinois. Thomas and Wilson first corresponded by letter from 1846-1856 then met and were in active fellowship from 1856-1862. However, in 1863 a disagreement between the two men concerning the judgment seat and the resurrection caused the groups associated with them to separate, and the rift was confirmed when the two groups registered (for the purposes of conscientious objection in the American Civil War) with different names in 1865.