Green Gang
As the leader of the Green Gang, Du dominated Shanghai's opium and heroin trade in the 1930s, and secretly funded the political career of Chiang Kai-shek. In contrast to his views on legality, Du was politically a staunch Confucian conservative. He had close ties with Chiang Kai-shek, who in turn had ties to both the Green Gang and other organised secret societies from his early years in Shanghai. Chiang forged political alliances throughout the 1920s, with some of the secret societies going as far as to offer their support in the 1927 Shanghai Purge. The resulting massacre ended the First United Front, and as a reward for Du's service, Chiang appointed him as the president of the National Board of Opium Suppression Bureau. The end result was that Du came to officially control the entirety of China's opium trade.