The Social Democratic Party of Germany (from 1875)
Although the leading figures of the “Eisenach” tendency in German social democracy had already been influenced by Marx and Engels, during its initial developmental phase (from Anti-Dühring in 1877—1878 to the Erfurt Program in 1891) “Marxism”, which was significantly shaped by Engels and later by Karl Kautsky, prevailed as the dominant ideology of the Social Democratic Party of Germany (SPD).
This period also roughly coincides with the Anti-Socialist Law. The SPD continued to undergo substantial change until 1914, and this led to the development of a number of competing currents. In 1917, the wing of the SPD that had refused to endorse the war split from the party to form the Independent Social Democratic Party of Germany (USPD).