Opium Suppression Movement Day is observed in Taiwan every June 3. This holiday commemorates the burning of opium during the First Opium War, which took place from 1839 to 1842. On this day in 1839, approximately 20,000 chests of opium were confiscated and destroyed by Chinese officials, a significant act in response to the opium trade that had led to widespread addiction in China. While the holiday is recognized in every city across Taiwan, it is not an official day off. The First Opium War arose due to conflicts between Britain and China over trade and diplomatic relations, ultimately resulting in the Treaty of Nanking, which opened the Chinese market to global commerce and solidified Britain's control over Hong Kong.