Ledebour was involved in the political leadership, along with Karl Liebknecht, of the attempt in Berlin to overthrow the government headed by Friedrich Ebert in January 1919.

This was poorly organised and was quickly defeated by the units of the German army and the Freikorps, and notably led to the murder of both Karl Liebknecht and Rosa Luxemburg.

Ledebour was also involved in front organizations of the KPD such as the World League against Imperialism and the International Workers' Relief (IAH).

During this period, he was involved in journalistic activism against the Nazi regime and called for unity between the KPD and SPD.

[7] In 1947, Ledebour spoke out in favor of the merger of the KPD and SPD and died shortly after in Bern in 1947 after a long illness.