August 1914 was a decisive turning point for the world socialist movement. A fundamental divide opened between reformists and revolutionaries when most parties of the Socialist International supported their own ruling classes in the world war.

This capitulation of supposedly Marxist parties, above all the German Social Democratic Party (SPD), was the product of an increasing identification with their own capitalist nation-state by party and trade union leaders. Well before August, these leaders had abandoned the interests of the working class and crossed over to the side of the capitalist class.

The initial socialist approach to war was developed by Karl Marx and Friedrich Engels before the rise of modern imperialism. The First International, in which Marx and Engels played a leading role, denounced standing armies as an incitement to militarism and championed popular militias with democratically elected officers. However, it backed the principle of national defence.

Marx and Engels supported the rising capitalist powers against semi-feudal reaction; in particular, they supported wars against tsarist Russia—the backbone of reaction. They also supported the North against the slaveholding South in the US Civil War and national rebellions in Ireland and Poland. They believed these progressive wars put workers in a better position to fight for freedom.

This approach was appropriate before the development of modern imperialist competition made national defence redundant for the likes of Britain, France and Germany. However, there was a considerable delay in socialists developing a new approach for the imperialist epoch.

Even Bolshevik leader Vladimir Lenin long held to elements of the old approach, viewing tsarist Russia as the main enemy. In 1904, he supported the victory of Japanese imperialism in the war with Russia.


The 1907 Stuttgart conference of the Socialist International adopted a resolution stating that, if war broke out, it was the duty of socialist parties “to intervene in favour of its speedy termination and to do all in their power to utilise the economic and political crisis caused by the war to rouse the peoples and thereby to hasten the abolition of capitalist domination”.

A worthy declaration is one thing; more important is what you do in practice. The International developed no clear guidelines for collective action and no common program when war erupted.

In Germany, Karl Liebknecht organised an anti-militarist campaign and published a crusading polemic Militarism and Anti-Militarism. Liebknecht received support from SPD youth groups but was stomped on by the leadership.

On the extreme left, French socialist Gustave Herve called for an insurrection in response to war, while the old Communard Edouard Vaillant called for a general strike. Lenin and Rosa Luxemburg recognised that this anarchist-style approach was unworkable. A general strike or insurrection can’t be summoned on command, let alone in the face of nationalist euphoria at the outbreak of war. 

From about 1907, the SPD increasingly accommodated to nationalism and colonialism. The party’s right wing argued that the latter was progressive, bringing “civilisation” to colonised peoples. The problem was not just the right wing, however. Europe’s best known socialist theorist, Karl Kautsky, a leading representative of the SPD centre, put forward the theory of ultra-imperialism.

He argued that the increasing economic integration of capitalist industry across borders and the growth of world trade made war less likely. According to Kautsky, only a few sectors of capital, such as the arms industry, supported war. This laid the basis for an alliance between socialists and supposedly progressive capitalists.

A test came with the 1911 Morocco crisis, when a German cruiser, the Panther, entered Agadir harbour in a direct challenge to French imperialism. The centrist SPD leadership refused to speak out against the provocation. In cities where the left was strong, protests were held. And when Luxemburg attacked the leadership’s prevarication, they were belatedly forced to act.

The left wing, led by figures such as Luxemburg, developed a rigorous critique of imperialism. But they concentrated their fire on the party’s right wing and didn’t clearly differentiate themselves from the Kautskyite centre.

The left viewed unity as sacrosanct. So the key differences in the socialist movement were fudged until the war. Even Lenin didn’t attempt to organise an international left in the prewar years.

As the imperial powers edged closer to conflict, the socialist parties didn’t prepare their ranks to combat the virus of nationalism. Having passively accepted the build-up to war, it was no great leap for party leaders to go over to outright support for their nation when war broke out—especially when faced with pro-war hysteria, the threat of repression that would destroy the unions and the workers’ organisations built in peaceful times.

By 1914, the SPD had 1 million members, an apparatus that employed 10,000 people and investments of 20 million marks (the German currency) in its enterprises. All were threatened if the party was outlawed.

The reformists sought theoretical justifications for their betrayals. The SPD declared that Germany was fighting a war of self-defence and pathetically hoped that that the war would end with “a peace which makes friendship possible with neighbouring peoples”.

A German victory, it was claimed, would aid Russian workers by provoking a revolution to overthrow tsarism. In France and Britain, reformists claimed that they were fighting a defensive war against reactionary Prussian militarism. Yes, a “defensive” war to protect their ruling classes’ colonial conquests from the rising power of Germany.


The scale of the betrayal left the small bands of socialists who held firm to internationalist principles shocked and extremely isolated. Marxists were confronted with the task of developing a thorough critique of imperialism and reformism, along with a strategic approach to the struggle against the war.

“The result was one of the most intense and creative debates in the entire history of socialist thought, a debate about alternative visions of revolutionary transformation in the circumstances of the twentieth century”, R. Craig Nation writes in War on war, his survey of the period. There was a flourishing of theoretical work including Lenin’s Imperialism, the highest stage of capitalism and Bukharin’s Imperialism and world economy.

The revolutionary left agreed on three key points. First, the First World War was an imperialist war that had to be opposed by workers in all countries. Second, the leaders of the social democratic parties had betrayed the working class. Third, a revolution was needed to end the war. However, there was a series of debates about revolutionary defeatism (supporting the victory of the opposing imperialist army over your own ruling class), the slogan demanding “peace”, the question of disarmament, national liberation struggles and the need for a new revolutionary international.

Lenin’s focus in the early years of the war was, correctly, on establishing a hard left pole of attraction that made no concessions to reformism and that combated any illusions about achieving peace without revolution. He is renowned for his ultra-radical sounding call for revolutionary defeatism.

Leading Bolsheviks disagreed with Lenin on defeatism—not just conservative figures, but the left of the party around Bukharin. In terms of the campaigning activity of Russian Bolshevik workers during the war, defeatism played little or no role.

“A textual analysis of 47 leaflets and appeals published illegally by Bolshevik militants between January 1915 and 22 February 1917 is most illuminating. Not a single leaflet mentioned ... the defeat of Russia being the lesser evil”, notes Robert B. McKean in St. Petersburg between the revolutions.

Virtually nobody on the Marxist left—including Leon Trotsky, Rosa Luxemburg and Karl Radek—supported defeatism. As Trotsky pointed out, socialists could oppose the war and support working-class mass action without embracing the confusing slogan of revolutionary defeatism.

Lenin abandoned talk of defeatism before returning to Russia after the February 1917 revolution. The Bolsheviks could not win over the mass of workers by such ultra-radical sounding slogans.

The labouring classes wanted peace, but they feared that a German victory would result in the defeat of the revolution. Indeed, by September 1917, sections of the Russian capitalist class backed a German invasion to crush the Bolsheviks.

At the start of the war, Lenin polemicised against the peace slogan and counterposed it to the slogan of “turn the imperialist war into civil war”. “Not ‘peace without annexations’”, he proclaimed, “but peace to the cottages, war on the palaces”.

Lenin viewed the talk of peace by centrists such as Kautsky as being in direct opposition to a workers’ revolution. Lenin correctly pointed out that, in a capitalist world, the only peace possible was an “imperialist peace” based on the balance of forces between the great powers.

The reformists claimed that they were for a “democratic peace” that involved the renunciation of all annexations. But this simply meant supporting the prewar status quo—the existing division of the spoils of empire.

On similar grounds, Lenin opposed calls for universal disarmament and the international arbitration of disputes, which were advocated by sections of the left. As well, Lenin, unlike many on the revolutionary left—including Luxemburg, Radek and Bukharin—backed nationalist rebellions in colonies such as Ireland. As for international arbitration, there was no neutral body capable of justly settling disputes. Any decision would merely reflect the balance of imperialist forces.

Lenin was correct that talk of a democratic peace was utopian under capitalism. And it was undoubtedly true that Kautsky and others were raising these slogans in opposition to a strategy of working-class struggle to end the war.

But that did not entirely settle the issue. As discontent rose over the collapse of living standards and the slaughter at the front, workers and the oppressed increasingly demanded peace. Revolutionaries could not turn their backs on those demands. Workers were not demanding peace out of pro-imperialist motivations or to prop up capitalism.

The Bolsheviks in their agitation in the factories could not simply denounce talk of peace as utopian. That would have cut themselves off from the masses they needed to win over, thereby aiding the reformists.

Lenin recognised that the Bolsheviks could not simply proclaim to the millions yearning for peace: “Turn the imperialist war into a civil war”. It was way too maximal. He now criticised the previous approach: 

“The masses take a practical and not a theoretical approach to the question. We make the mistake of taking the theoretical approach ... We Bolsheviks are in the habit of taking the line of maximum revolutionism. But that is not enough.”

The Bolsheviks practical program became: no class peace, no participation in wartime governments, no war credits (funding), carry out illegal work, encourage fraternisation at the front between soldiers of opposing armies. The key slogans for the October 1917 revolution famously became “bread, peace and land” combined with the means to achieve those goals: “All power to the soviets”.

This concrete program was a product of the tactical flexibility of Lenin and the Bolsheviks as they applied their principled revolutionary politics to the consciousness of the masses as they moved towards revolutionary conclusions.

In the aftermath of the February revolution, the Bolsheviks were confronted with another vital issue—what Lenin called the “honest defencist” sentiments of many soldiers. These soldiers believed it was necessary to fight on, not for the imperialist goal of seizing territory, but to protect the gains of the revolution.

The Bolsheviks did not retreat from their opposition to the war, but they had to relate to these genuine concerns. The Bolsheviks did not call for mutinies or desertions. The war would not be ended by soldiers “sticking their bayonets in the ground”—that was pure demagogy, an anarchist or pacifist idea.

The war could be ended only by revolutions in several countries. The first step would be for workers and soldiers to take power in Russia. In the months before the October revolution, as tsarist officers conspired to open the front for the Germans to capture St Petersburg, it meant Bolshevik-influenced troops fighting hard to prevent German advances.


With the collapse of the Socialist International into support for the war, Lenin immediately called for a new revolutionary international. But the forces of the revolutionary left were too small at the start of the war to make that a practical proposition.

Small openings for the revolutionaries came at the International Women’s and Youth conferences in early 1915. At the Women’s conference, Inessa Armand pursued what was to become the Bolsheviks’ tactical orientation: challenging the dominant moderate consensus but striving to avoid an open breach.

The goal was to use the conferences as a platform to air an alternative viewpoint, to recruit supporters and to exert some influence on the final resolutions. The Women’s and Youth conferences helped lay the basis for a serious step forward for the anti-war left, the September 1915 Zimmerwald conference in Switzerland.

The key figure behind the Zimmerwald movement, Robert Grimm of the Swiss Socialist Party, stood for “class struggle not civil truce”, but he was not a revolutionary and opposed organisational splits. The conservative wing of Zimmerwald was for restoring the Socialist International around the common denominator of “peace”. 

Even some left-wing delegates who Lenin laboriously fought to cohere into a left bloc did not want to totally cut off their links with the Socialist International. Recognising this, Lenin amended his conditions for affiliation to the left bloc to: unconditional condemnation of reformism and social chauvinism, a revolutionary action program and the repudiation of national defence.

The Zimmerwald manifesto drafted by Trotsky was a compromise. It raised democratic peace slogans and did not call for civil war. Lenin voted for the manifesto as a step forward but criticised its limitations.

Zimmerwald revived the spirit of the anti-war left. By the time of the second anti-war conference at Kienthal, Switzerland, in April 1916, the tide had shifted substantially because of an upsurge of working-class protests against the war and food shortages. The arguments of the left bloc built by Lenin were now going with the flow of events.

The Zimmerwald left, despite an ongoing lack of cohesion, was increasingly critical of the socialist centre. The basis was being laid for the formation of the Communist International.

The revolutionaries’ argument that the war could be ended by working-class revolts was decisively proved over the next two years by the October 1917 revolution in Russia, the November 1918 German revolution and a series of further revolts that swept Europe and much of the world.