The Second International and the socialist movement across Europe

The Second International was founded in Paris in July 1889, coinciding with the centennial of the French Revolution, and it brought together socialist and social-democratic parties from numerous European countries as a looser federation of national parties, unlike the union-centered First International. Its founding congress declared May 1st International Workers' Day in homage to the Haymarket martyrs of Chicago, four anarchists executed in 1887 after a bombing during a demonstration for the eight-hour workday; the first international commemoration of May Day was held in 1890. The German SPD established itself as the organization's most influential party, and among its leading theorists were Karl Kautsky, Eduard Bernstein, Jean Jaurès, and Georgi Plekhanov.