Complex sentence: At the time, opium was legal and considered relatively safe in the West and the trade hungry British Empire considered China's refusal to allow imports of the drug an affront to their principals of free trade espoused by Adam Smith and other leading thinkers of the day.
Split into simpler sentences: At the time, opium was legal and considered relatively safe in the West. As a result, the trade hungry British Empire considered China's refusal to allow imports of the drug an affront to their principals of free trade espoused by Adam Smith and other leading thinkers of the day.