[1] Liebknecht participated in the German Revolution of 1848, and after its defeat lived in exile, where he met Karl Marx and Friedrich Engels.

In 1875, Liebknecht helped to unite the SDAP and ADAV to form the party which later became the SPD, and was largely responsible for drafting its inaugural Gotha Program.

The life story of his maternal great-uncle, the Protestant pastor and democratic activist Friedrich Ludwig Weidig, influenced young Liebknecht's social and political attitudes relatively early on.

He then became a member of the Badische Volkswehr and an adjutant of Gustav von Struve and fought in the ill-fated Reichverfassungskämpfe ("federal constitution wars").

After the revolutionaries' defeat, he escaped to Switzerland and became a leading member of the Genfer Arbeiterverein (Worker's Association of Geneva), where he met Friedrich Engels.

After being re-elected to the Reichstag in 1874, Liebknecht played a key role in the merger of the SDAP and Lassalle's ADAV into the Socialist Workers' Party of Germany [de] (Sozialistische Arbeiterpartei Deutschlands, SAPD) in Gotha in 1875.

He also became publisher of the newly founded party organ Vorwärts (Forward), arguing for the integration of Marxist theories into the SAPD's program in his articles.

Liebknecht used his position as a Reichstag member to criticize the political situation and opposed the tendencies in his own party toward anarchism on the one hand and accommodation with Bismarck on the other.

Maintaining a radical and unified stance, the SAPD emerged from outlawry in 1890 as the Social Democratic Party of Germany (Sozialdemokratische Partei Deutschlands, SPD), taking 20% of the vote in the Reichstag election.

[citation needed] His grave now forms part of the Memorial to the Socialists (German: Gedenkstätte der Sozialisten) in the Friedrichsfelde Central Cemetery, Berlin.