The Golden Age of Socialism
. . . was the quarter century between 1890 and 1915.
Between 1820 and 1890 the nascent movement, typically, endured furious debates between theorists and activists for influence and hegemony. There were advocates of communism, syndicalism, anarchism, Georgism, Fabianism, the “nationalism” of Edward Bellamy, etc.
But by 1890 Marxism had won out as canonical. This enabled an unusual degree of unity in regard to theory and praxis.
The central authority was the German Social Democratic Workers Party (SPD), founded in 1889. The chief theoretician was Karl Kautsky. He guided the development of the key document, The Erfurt Program, and everybody was reading his magazine Die Neue Zeit (The New Times).
During that quarter-century many socialist parties were founded and thrived (the Socialist Party of America was founded in 1901).
But the unity didn’t last long. Movements and belief systems have always suffered contentions and schisms. When WWI broke out in 1914 the various socialist parties differed in regard to orientation. Then they differed in attitude toward the 1917 Bolshevik Revolution in Russia. Then they differed in regard to the Stalin-Trotsky split. And then about what positions to take during the Cold War.
In 1912, in the United States, Eugene Debs got 6% of the vote running for president on the Socialist Party ticket. No one has done better since. In Europe the socialists were on the way toward becoming majorities in some parliaments. It must have seemed inevitable that one society after another would go socialist before too long.
https://jacobin.com/2020/10/rudolf-hilferding-finance-capital-kautsky-marx
During the first decade of the twentieth century, Europe’s socialist parties, organized within the Socialist International, were experiencing unprecedented growth. In rapidly industrializing Germany, the SPD’s membership exploded from 384,000 in 1906 to over 1 million in 1912, while the party’s electoral strength increased steadily until it peaked in 1912 at almost 35 percent of the vote, making it by far the largest party in the parliament.