As the opium traffic grew in the late 18th and early 19th centuries, the Hoppo was caught between conflicting demands. On the one hand, the British Parliament ended the East India Company's monopoly in 1834 and traders now demanded free trade and low, fixed tariffs; on the other hand, the Manchu court expected the Hoppo to control the foreign traders, stop Chinese smuggling, eliminate the opium trade, but continue to supply substantial revenue. Foreign objections to monopoly and his irregular impositions were among the causes of the Opium War (1839-1842). The Treaty of Nanking (1842) ended the Canton System but the office of Hoppo was not abolished until 1904 as part of the reforms at the end of the dynasty.