The blending of labor and socialism in most of the countries of Europe was not, however, a work of months, but of decades. The first great effort to accomplish that task occurred in 1864, when the International Working Men's Association was launched in St. Martin's Hall in London. During the years from '47 to '64, Marx and Engels, with their little coterie in London and their correspondents in other countries, spent most of their time in study, reading, and writing, with little opportunity to participate in the actual struggles of labor. Marx was at work on "Capital" and schooling, in his leisure hours, a few of the notable men who were later to become leaders of the working class in Europe. It was a dull period, wearisome and vexatious enough to men who were boldly prophesying that industrial conditions would create a world-wide solidarity of labor. The first glimmer of hope came with the London International Exhibition of 1862, which brought together by chance groups of workingmen from various countries. The visit to London enabled them to observe the British trade unions, and they left deeply impressed by their strength. Furthermore, the Exhibition brought the English workers and those of other nationalities into touch with each other. How much this meant was shown in 1863. When the Polish uprising was being suppressed, the English workers sent to their French comrades a protest, in answer to which the Paris workmen sent a delegation to London. This gathering in sympathy with Poland laid the foundations for the International. Nearly every important revolutionary sect in Europe was represented: the German communists, the French Blanquists and Proudhonians, and the Italian Mazzinians; but the only delegates who represented powerful working-class organizations were the English trade unionists. The other organizations, even as late as this, were still little more than coteries, of hero-worshiping tendencies, fast developing into sectarian organizations that seemed destined to divide hopelessly and forever the labor movement.