There is one factor in the collapse of the Second International the is still unclarified. It dwells at the heart of all the events that the Party has passed through.
The dependence of the proletarian class movement, particularly in its economic conflicts, upon the scope and the successes of the imperialistic policy of the state is a question which, as far as I know, has never been discussed in the Socialist press. Nor can I attempt to solve it in the short space of this work. So what I shall say on this point will necessarily be in the nature of a brief review.
The proletariat is deeply interested in the development of the forces of production. The national state created in Europe by the revolutions and wars of the years 1789 to 1870 was the basic type of the economic evolution of the past period. The proletariat contributed by its entire conscious policy to the development of the forces of production on a national foundation. It supported the bourgeoisie in its conflicts with alien enemies for national liberation; also in its conflicts with the monarchy, with feudalism and the church for political democracy. And in the measure in which the bourgeois turned to “law and order”, that is, became reactionary, the proletariat assumed the historical task the bourgeoisie had left uncompleted. In championing a policy of peace, culture and democracy, as against the bourgeoisie, it contributed to the enlargement of the national market, and so gave an impetus to the development of the forces of production.
The proletariat had an equal economic interest in the democratizing and the cultural progress of all other countries in their relation of buyer or seller to its own country. In this resided the most important guarantee for the international solidarity of the proletariat both in so far as final aims and daily policies are concerned. The struggle against the remnants of feudal barbarism, against the boundless demands of militarism, against agrarian duties and indirect taxes was the main object of working-class politics and served, directly and indirectly, to help develop the forces of production. That is the very reason why the great majority of organized labour joined political forces with the Social Democracy. Every hindrance to the development of the forces of production touches the trade unions most closely.
As capitalism passed from a national to an international-imperialistic ground, national production, and with it the economic struggle of the proletariat, came into direct dependence on those conditions of the world market which are secured by dreadnaughts and cannon. In other words, in contradiction of the fundamental interests of the proletariat taken in their wide historic extent, the immediate trade interests of various strata of the proletariat proved to have a direct dependence upon the successes or the failures of the foreign policies of the governments.
England long before the other countries placed her capitalist development on the basis of predatory imperialism, and she interested the upper strata of the proletariat in her world dominion. In championing its own class interests, the English proletariat limited itself to exercising pressure on the bourgeois parties which granted it a share in the capitalist exploitation of other countries. It did not begin an independent policy until England began to lose her position in the world market, pushed aside, among others, by her main rival, Germany.
But with Germany’s growth to industrial world-importance, grew the dependence of broad strata of the German proletariat on German imperialism, not materially alone but also ideally. The Vorwärts wrote on August 11th that the German workingmen, “counted among the politically intelligent, to whom we have preached the dangers of imperialism for years (although with very little success, we must confess)” denounce Italian neutrality like the extremest chauvinists. But that did not prevent the Vorwärts from feeding the German workingmen on “national” and “democratic” arguments in justification of the bloody work of imperialism. (Some writers’ backbones are as flexible as their pens.)
However, all this does not alter facts. When the decisive moment came, there seemed to be no irreconcilable enmity to imperialistic policies in the consciousness of the German workingmen. On the contrary, they seemed to listen readily to imperialist whisperings veiled in national and democratic phraseology. This is not the first time that Socialistic imperialism reveals itself in the German Social Democracy. Suffice it to recall the fact that at the International Congress in Stuttgart it was the majority of German delegates, notably the trade unionists, who voted against the Marxist resolution on the colonial policy.  The occurrence made a sensation at the time, but its true significance comes out more clearly in the light of present events. Just now the trade union press is linking the cause of the German working class to the work of the Hohenzollern army with more consciousness and matter-of-factness than do the political organs.
As long as capitalism remained on a national basis, the proletariat could not refrain from cooperation in democratizing the political relations and in developing the forces of production through its parliamentary, communal and other activities. The attempts of the anarchists to set up a formal revolutionary agitation in opposition to the political fights of the Social Democracy condemned them to isolation and gradual extinction. But when the capitalist states overstep their national form to become imperialistic world powers, the proletariat cannot oppose this new imperialism. And the reason is the so-called minimal programme which fashioned its policy upon the framework of the national state. When its main concern is for tariff treaties and social legislation, the proletariat is incapable of expending the same energy in fighting imperialism that it did in fighting feudalism. By applying its old methods of the class struggle—the constant adaptation to the movements of the markets—to the changed conditions produced by imperialism, it itself falls into material and ideological dependence on imperialism.
The only way the proletariat can pit its revolutionary force against imperialism is under the banner of Socialism. The working class is powerless against imperialism as long as its great organizations stand by their old opportunist tactics. The working class will be all-powerful against imperialism when it takes to the battlefield of Social Revolution.
The methods of national-parliamentary opposition not only fail to produce practical results, but also cease to make an appeal to the labouring masses, because the workers find that, behind the backs of the parliamentarians, imperialism, by armed force, reduces the wages and the very lives of the workers to ever greater dependence on its successes in the world market.
It was clear to every thinking Socialist that the only way the proletariat could be made to pass from opportunism to Revolution was not by agitation, but by a historical upheaval. But no one foresaw that history would preface this inevitable change of tactics by such a catastrophal collapse of the International. History works with titanic relentlessness. What is the Rheims Cathedral  to History? And what a few hundred or thousand political reputations? And what the life or death of hundreds of thousands or of millions?
The proletariat has remained too long in the preparatory school, much longer than its great pioneer fighters thought it would. History took her broom in hand, swept the International of the epigones apart in all directions and led the slow-moving millions into the field where their last illusions are being washed away in blood. A terrible experiment! On its result perhaps hangs the fate of European civilization.
Although the Stuttgart Conference of the Second International (1907) was able to achieve unanimity on the attitude to war, on the colonial question it was sharply divided. An anti-colonial resolution was passed 127 to 108, with the Germans (though divided among themselves) voting solidly for the “colonialists”.
In September 1914, the Cathedral of Rheims, where every French King from Clovis to Louis XVI had been crowned, was shelled by German guns.