[2] He took command of Zhejiang and Fujian's military forces as dūdū (都督)[3] in February 1624 and immediately took a hard line against the Dutch East India Company stronghold on Penghu Island in the Pescadores.
[4] Yu Zigao was on friendly terms with the merchant and pirate Li Dan[2] and used his position to enrich himself.
[5] In 1627 and 1628, Li Dan's protégé[2] Zheng Zhilong launched a series of massive pirate invasions of the Fujianese coast, maintaining his popularity by targeting the wealthy and reserving some of the plunder for assistance to the poor.
[6] He sank hundreds of Ming vessels and captured several county seats around Quanzhou and Zhangzhou.
[6] (Yu himself had difficulty at the imperial court owing to his association with the eunuch faction under Wei Zhongxian.