Pressured by Qing fleets, Zheng fled to Taiwan in April 1661 and defeated the Dutch in the Siege of Fort Zeelandia, expelling them from Taiwan and setting up the Kingdom of Tungning. Great care was taken to symbolise support for the Ming legitimacy, an example being the use of the term "guan" instead of "bu" to name departments, since the latter is reserved for central government, whereas Taiwan was to be a regional office of the rightful Ming rule of China. Zheng Jing dutifully complied with the prescribed procedures for Ming officials by regularly presenting reports and paying tribute to the absent Ming Emperor. His originally stated intentions for conquering Taiwan from the Dutch also included the desire to protect Chinese settlers in Taiwan from maltreatment by the Dutch. The Ming dynasty Princes who accompanied Koxinga to Taiwan were the Prince of Ningjing Zhu Shugui and Prince Zhu Hónghuán (朱弘桓), son of Zhu Yihai.