What made these particular acts of aggression so odious was, as I discovered in shock several years ago, they were not fought for the obvious reasons you would think; that the Chinese has opium and the British sent some military to take it from them. The reality is much more hideous then that.
As the previous poster mentioned, the British had little the Chinese wanted to trade for, and the Brits wanted Chinese tea in huge quantities. What the British eventually settled on was Afghanistan opium, which the Chinese had a taste for. The problem started when the Chinese leaders, seeing the destruction that opium addiction was doing to their people, tried to stop the trade of opium and reign in the millions of ruined lives it was causing.
The British responded, rather poorly I'd say, by going to war with the Chinese to force them to continue to trade the opium for the tea and thusly keep their people enslaved to the drug. It's a rather unbelievable premise for going to war actually, but in 1839 that's what they did.
They won, thus insuring several more generations of totally ruined Chinese addicts. I always think that this pretty much represents government and big business working in tandem at its most evil worse.