[A 1676 canon recovered in Kinmoy, was possibly in the arsenal of the army of Koxinga's eldest son, 鄭經Cheng Jing]
According to 明史 the History of Ming [Dynasty], Koxinga had ruled despotically, citing as the evidence was that 75 of his generals and commanders were executed with no mercy, without any regards to their previous merits. This "history" was of course written by Qing historians who must tow the official lines. Indeed, these military men were put to death between the 9th Month of 1649 and the 1st Month of 1661. However, they were justifiably dispatched for cowardice, defeat, retreating before or surrendering to the enemy, or desertion. In addition, there were also 9 who were demoted for lesser offenses and 6 killed for corruption. Often ignored was the fact that, at the same time, more than 300 rewards and promotions, far out-numbering the punishment, had also been distributed. The Qing and the Dutch literature had also attempted to smear Koxinga's name by baselessly accusing him of slaughtering defenseless civilians in fallen cities/towns, exacting excessive taxes from the common people, and committing atrocities against the Aborigines in Taiwan.
Koxinga's close subordinate General 馬信 once counseled that "立國之初, 宜用寬典"[in the beginning of nation-building, it is better not to enforce the law too harshly]. Koxinga had retorted that "立國之初，法貴於嚴，庶不至流弊。俾後之守者自易治耳" [on the contrary, during nation-building, strict laws are needed, to avoid problems for those later to follow and govern]. Some of these killings had fostered resentment that led to defection. The most well-known turncoat was Shi-Lang whose father and brother were both killed by Koxinga, in reprisal for Shi-lang's executing a trusted lieutenant of Koxinga's. Shi-lang later went over to the Qing. He eventually defeated Koxinga's grandson and in essence handed Taiwan over to the Manchurian.
Koxinga's just rule was also aided by his most faithful wife, Lady Tung. She had advised, or more likely, requested that Koxinga order his men not to molest, rob, or rape civilians. This was complied and all violations were again punishable by death. His army was known not to disturb the populace, even known to politely yield the right of way to women and children. Fundamentally, Koxinga's righteousness was shaped in his younger days by the teachings of Confucianism; although, at times, he would go overboard and became overly self-righteous. For example, even adultery carried a death sentence. This intense dislike of mildly aberrant human behavior was to cause severe consequences.
In fact, an incident that was to change the course of the history eventually occurred in Koxinga's household. His eldest son 鄭經Cheng Jing had a secret affair with his own wet nurse and together they had produced a son. The birth of the next heir-apparent was initially greeted with joy by the brand new grandfather, Koxinga. Unfortunately, the wet nurse, regrading herself as the mother of the eventual heir, was quite disrespectful to Cheng Jing's principal wife Lady Tang. Tang's father would not tolerate such insolence and reported the affair to Koxinga stating that, under the Confucian moral codes, the affair was considered a grave violation of the family order, in effect, a form of mother-son incest. Koxinga flew into a rage and ordered death penalty for the wet nurse and the now illegitimate child. 鄭經, however, disobeyed the order. Koxinga then decreed that all three, the parents and the baby, must die. Plus, of all people, that the most revered Lady Tung must pay with her life for not bringing up Cheng Jing properly. Luckily, both time and distance came to the rescue. At that time, Koxinga was finishing up his operation against the Dutch in Taiwan, while the family members were back home in Amoy. Koxinga's lieutenants also refused to carry out what appeared to be an unreasonable command from him. And before any further action could be taken, Koxinga passed away (on the 8th Day of the 5th Month, 1662), thus sparing the lives of all involved.
After a further dispute with Koxinga's brother 鄭世襲 over the inheritance of the Ming-Cheng Kingdom, Cheng Jing eventually assumed the title and with it the rights of 延平王 the Yan-Pin Kingship and became the King of Tung-Ning [Taiwan] for the next 20 years until his death in 1681.
Koxinga, in his short life, never really ruled Taiwan which was in fact re-built by Cheng Jing's administration. With a strong mother, Lady Tung, by his side counseling on most if not all issues, Cheng Jing tried hard to govern and to continue Koxinga's mission of recovering Mainland China. Regrettably, for having accomplished very little of either, he retreated into womanizing, indulging in the pursuits of worldly pleasure that eventually led to his early demise.
Lady Tung was apparently a very demanding mother. After the failed campaign of attacking China in 1676, Cheng Jing was scolded publicly by her: "七府速敗，兩島亦喪，該你無權略果斷，不能任人，致左右各樹其黨耳!" [Losing the battle and the territories was all because of your ineptitude and indecision, you cannot use the right persons for the right tasks only to see them gang up fighting each other!] History recorded that Cheng Jing had remained silent, unable to reply.
In a bloody court drama, after Cheng Jing's death, Lady Tung instructed that his then 17-year-old first-born (the one by the wet nurse) 鄭克臧 be killed and the 12-year-old second son 鄭克塽 installed as the King - so as not to taint the blood line.
This was the beginning of the end of the Ming-Cheng Dynasty.
