I've heard of the Opium Wars many times before. They're probably still fairly damaging to Sino-Anglo relations. A far away nation attacked and defeated a large and historic yet un-modernised empire to open ports for them to sell harmful drugs and they took a port (Hong Kong) so that their presence was still felt even after they had left. It was pretty humiliating!
It's hard to paint Britain as anything but a total ******* in this case.
Honestly, the only time I've heard about the Opium Wars was when Cameron and co. went on an official visit to China around Remembrance Day a few years ago, and some people took offence when they refused to remove their poppies.
As wars go, the Opium Wars were a truly dark chapter in British history. The Treaty of Nanjing, which concluded the war, also opened up China to foreign colonialism and intervention which left a lasting scar on the Chinese nation.
But they did have one positive, though somewhat ironic, benefit - had it not been for the Opium War, then Hong Kong (and Macau) would not have developed into the only examples of liberty, freedom and democracy within China. In a strange and unexpected way, a war between two of the oldest nations in the World led to the birth of a completely new society and national community in Hong Kong.
Just to add, I'd be glad to also hear from those who haven't heard of the opium wars...