Wang Mang seized the Han throne in 9 CE and immediately got to work proving that central planning destroys faster than any invading army. His Xin dynasty lasted fourteen years. The lesson cost millions of lives.
Mang nationalized land and redistributed it to peasants, abolishing private ownership in a single imperial decree. The result: farmers stopped investing in their fields. Why drain a well you do not own? Agricultural output collapsed precisely when population pressure demanded more food, not less.
He fixed grain and cloth prices to "protect the poor." Merchants stopped selling at a loss, supply dried up, and the poor he claimed to protect starved. Price suppression destroys market signals and produces shortage.
Currency debasement compounded everything. Mang reformed coinage four times between 9 and 14 CE, replacing heavier bronze coins with lighter ones while demanding the old exchange values hold. Chinese merchants figured out Gresham's Law immediately and hoarded the old metal. Trade seized up.
His salt and iron monopolies, justified as revenue tools, strangled the artisan economy that Han prosperity had built over two centuries. State monopolies run politically, which means they run badly.
By 23 CE, famine and peasant revolt erased him and his dynasty entirely. The Red Eyebrow rebels did not read economic theory. They just noticed they were hungry. Mang gave them every reason to be, having replaced a functioning market order with fourteen years of bureaucratic improvisation, each intervention generating the crisis that justified the next one.