The 1920s were a heady time for those fighting against imperialism. World War I had shaken the foundations of a world order based on imperial formations. Three multinational empires—the Russian, Austro-Hungarian, and Ottoman—lay shattered, their territories reshaped by revolutionary forces that advocated the principle of the self-determination of nations. A fourth empire, the German, was stripped of its overseas territories and reborn as a republic. And the failure of the peace treaties to fulfill the aspirations of the millions who had mobilized against imperialism in 1919 left its enemies casting about for other avenues of attack. At the same time, the Bolshevik Revolution had transformed the vast multinational domain of the Romanovs into a Union of Soviet Socialist Republics. The newly formed Soviet Union and the Communist International (Comintern) it led posed a sharp challenge to domestic and international orders predicated on the logic of capitalism and imperialism and dominated by Britain, France, and the United States.

The League Against Imperialism (LAI) was born in that period at the intersection of the Comintern's commitment to the promotion of world revolution, on the one hand, and the escalating resistance to empire across large swaths of Asia and Africa, on the other. In particular, Comintern officials recognized the potency of anti-imperial sentiment in the protests against foreign influence that erupted in China on May 30, 1925; in the ongoing Rif War in North Africa; and in the outbreak of the Syrian revolt against French rule in the Levant. The League Against Imperialism, which emerged from a meeting convened in Brussels in 1927 by Comintern organizers, was therefore in one sense an example of the transformative impact of the Bolshevik Revolution on international society in the wake of the collapse of the Wilsonian moment.

Only a minority of those who attended the conference, however, were committed communists. At first, the LAI, following Moscow's united front policy, was willing to reconcile the class-based critique of capitalism with the claims for self-determination based on distinctions of national identity. Only months after the Brussels meeting, however, the united front began to fray, most spectacularly in the break between the Chinese Nationalists, led by Chiang Kai-shek, and the Chinese Communist Party, a break signaled with the bloody purge of Chinese communists by Nationalist forces in Shanghai in April of 1927, only weeks after the Brussels conference adjourned.