The two Opium Wars were between China and <u>England</u>.
The first war developed from 1839 to 1942, and the second, in which France allied with England, started over a decade later in 1839 and ended in 1860. Both wars ended with beneficial results for Britain and not for the Qing Dynasty of China, which after its first defeat not only had it to increased the treaty ports so Britain could trade and reside, but they had to cede Hong Kong to them as well; The outcomes of the second war weren't beneficial either: Chinese was forced to open more ports to British, to allow them to travel in their country, and legalize the opium trade, which started the wars in the first place.
Opium wars were wars between China and the United Kingdom of Great Britain and Ireland over the right to trade in China.
So, technically, the correct answer is the United Kingdom of Great Britain and Ireland, but I guess, "England", which was part of is is also a good answer.
