The article attempts to theoretically explain the origins of the nationalist and historicist turn of the Chinese mathematician Wu Wen-Tsun (born 1919). Wu returned to China from France in 1951 as an internationally recognized expert on algebraic topology, but his career was frustrated by political disruption and isolation from international research, especially during the Cultural Revolution (1966–76). After he studied ancient Chinese mathematics during the 1974 campaign against Confucianism (Pi Lin Pi Kong 批林批孔), he defended its relevance for modern mathematics and set out to demonstrate it in his own work. This coincided with Wu's reorientation from algebraic topology to mechanization of geometric proofs. Wu claimed that ancient Chinese mathematics inspired the method he developed, both by its general style and by specific techniques. His use of ancient Chinese mathematics was connected to his calls for an independent mathematical tradition in China. I argue that he turned to nationalism to protect himself from the “uneven development” of mathematics, in analogy to Ernest Gellner's theory of nationalism. The early success of his method of mechanization, however, resulted in more dependence on world mathematics, and a revival of ancient Chinese mathematics has not occurred.