Career
In 1592, nine days into the Japanese invasion of of Korea, he formed a militia to fight against the Japanese army. In 1585 Jeong passed a gwageo for the selection of officials and became an officer of the military training department of Hanseong (hanseongbupanyun). Next year, he was promoted to an officer of the book publishing department of Hongmungwan (hongmungwansuchan), and then he was in charge of dual positions, a reporting officer at Saganwon (Saganwonjeongwon) and a junghakgyosu.
In the next year, he was dispatched to the northeastern border as a crops commander of this region.
Fuming at the revolt, Jeonng put together a righteous army with seonbis. They totally reclaimed the northeastern province by winning at Baegtapgyo in the next year.
In 1624, he died while being tortured after he was arrested and falsely accused of participating in a revolt of Yi Gwal. Long after, he was posthumously reinstated after the accusation was proved unfounded.
