Despite – or perhaps because of – the deep impact made by his lectures, Steffens was not made welcome by the Danish authorities. He moved back to Germany and took up a professorship at the University of Halle in 1804, to return to Denmark only occasionally. During the Battle of Leipzig (1813) he enlisted in the Prussian Army as a second lieutenant, and he was present at the capture of Paris the following year. He was professor of physics at Breslau from 1811 until 1832, when he accepted an invitation to Berlin.