Drawing on little known archival sources, this work brings to the fore the salience of a schism in the Indonesian communist movement between pro-Moscow loyalists and "national-communists" reaching back to the 1920s, which survived even the Japanese occupation and surfaced in the throes of the National Revolution (1945–49). At the heart of the rift lay contrasting visions of revolutionary tactics, the salience of Islam in an Islamic majority society, the vexed question of alliance between leftists and other anti-colonial forces, and even the concept and definition of state and national ideology. As such, we cannot ignore the lineages of Marxism in the National Revolution, which trace their roots to the pioneer actions on Java by Dutch communists, themselves influenced by the Bolshevik Revolution. Contrary to the image of a non-revolutionary peasantry and a nationalist leadership broken or tamed by colonial carceral practices, the picture that emerges is one of acute agency on the part of an awoken population at a critical historical moment at the end of World War II.