Wilhelm Martin Philipp Christian Ludwig Liebknecht (29 March 1826 – 7 August 1900) was a German socialist and one of the principal founders of the Social Democratic Party (SPD). His political career was a pioneering project combining Marxist revolutionary theory with practical, legal political activity. Under his leadership, the SPD grew from a tiny sect to become Germany's largest political party. He was the father of Karl Liebknecht and Theodor Liebknecht.
Liebknecht was born in 1826 in Gießen, the son of Katharina Elisabeth Henrietta (née Hirsch) and Hessian public official Ludwig Christian Liebknecht. Liebknecht grew up with relatives after the death of his parents in 1832. From 1832 to 1842, he went to school at the Gymnasium of Gießen, then began studying philology, theology and philosophy in Gießen, Berlin and Marburg. After some trouble with the authorities as a result of participating in student radicalism, Liebknecht decided to emigrate to the USA.
While on a train to a port city, quite by chance, he met the headmaster of a progressive school in Zurich, Switzerland, and Liebknecht impulsively decided to accept an offer to be an unpaid teacher at that school. Thus he found himself in Switzerland in 1847 as a civil war began in that country. He reported these events for a German newspaper, the "Mannheimer Abendzeitung", beginning a career in journalism that he would pursue for the next five decades.
When revolution erupted in Paris in February 1848, Liebknecht hurried to the scene. He arrived too late to do much in Paris, but he did join a legion that was traveling to Germany to instigate revolution there. During that poorly planned expedition, he was arrested in Baden and charged with treason. On the eve of his trial, revolution erupted once more, and a mob secured his release. 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.