Answer:
What caused the Second Opium War were the harsh treaties imposed after the First Opium War.
Explanation:
The Second Opium War was an armed conflict between Great Britain and France, on the one hand, and the Qing Dynasty of China, on the other.
Both the French agreement known as the Huangpu Treaty and the US pact called the Wangxia Treaty, signed after the First Opium War, contained clauses that allowed the renegotiation of these treaties after twelve years. In an effort to expand its territories in China, the United Kingdom asked the authorities of the Qing dynasty to renegotiate what was agreed in the Treaty of Nanking, in 1842.
The British demands included that they could exercise free trade throughout China, legalize the commercialization of opium, abolish taxes on foreigners for internal transit, suppress piracy, regulate the traffic of coolies (semi-slave workers) and allow the British ambassador to reside in Beijing, among other things. The court of the Qing rejected the demands presented by the United Kingdom, France and the United States.
Because of this, a coalition was formed, with the aim of pressuring the Qing to sign those pacts.
