In 1856, after working as a private teacher, Johannes became teacher at the judiciary school of Slesvig. He had to leave this position due to the War of 1864. In 1867 he was appointed headmaster of Borgerdydsskolen at Christianshavn, a position he held to his death. In 1887 he became honorary doctor at the university and in 1892 he was elected a member of the citizen representation in Copenhagen.