Karlstadt operated as a church reformer largely in his own right, and after coming in conflict with Luther, he switched his allegiance from the Lutheran to the Reformed camp, and later became a radical reformer before once again returning to the Reformed tradition. First, he served as one of many Lutheran preachers in Wittenberg. He travelled widely, but only within the borders of the Holy Roman Empire, visiting German-speaking, French-speaking and Italian-speaking lands. By the end of his life he had allied himself with Heinrich Bullinger in Switzerland and worked in Basel, where he eventually died. Despite coming closer to the Reformed tradition by the time of his death, Karlstadt maintained his own distinct understanding on many theological issues throughout much of his life.