Born Dec. 30, 1812, in Weinbach; died Apr. 29, 1870, in London. Figure in the German and international working-class movement.
From his early youth Schapper led the life of a professional revolutionary. He helped found the League of the Just in 1836, the German Workers’ Educational Society in 1840, and the Fraternal Democrats in 1845, and he took part in the activities of all three organizations. He was among those who invited K. Marx and F. Engels to reorganize the League of the Just.
In 1847, Schapper became a member of the Communist League. He was chairman of the league’s First and Second Congresses and a member of the league’s Central Committee. During the Revolution of 1848–49, he became a leader of the Cologne Workers’ Union.
After the defeat of the revolution, Schapper fell under the influence of voluntaristic and conspiratorial ideas; together with A. Willich, he led an adventuristic sectarian faction within the Communist League. In 1856, however, he realized that he had been in error and resumed friendly relations with Marx and Engels. In 1865, Schapper became a member of the General Council of the First International.