The Spanish Second Republic, 1931-1939, has been written about widely and remains mired in antifascist, anti-communist, and historical memory controversies. A deep dive into the Soviet, British intelligence and other European archives, this new book brings the majority consensus among historians of the Second Republic into question and sheds new light on the scale of Soviet communist activity in Spain before the outbreak of war in July 1936. Providing an in-depth analysis of Comintern (RGASPI) and other European archival documentation, much of which has not been discussed until now, Gustavo Martín Asensio here demonstrates the growing and fundamentally subversive activity of the Comintern within the socialist union and party, the armed forces and cultural influencers which culminated in the spring of 1936.