Marshall Jevons at The Bayesian Heresy has posted a link to a podcast from the BBC regarding the Opium Wars. My thoughts on the relevancy of learning about this subject:
The subject of the Opium Wars is very relevant now as the world's entered the 21st century. As you know, opium and its derivatives are hard-core drugs, and in most countries these days are illegal. Yet the global trade in opiates and other illegal drugs is enormous. One of the unintended consequences of the US invasion of Afghanistan is that Afghanistan has regained its position as one of the world's major suppliers of opium.
Hypothetically, if drug cartels around the world formed an alliance, I believe they would have enough cash to put together a fairly significant military force. Plus, government agencies at all levels are rife with individuals who are on the payrolls of drug cartels. So, it is not out of the realm of conceivability that a new drug war could take place, where an "Axis of Suppliers", if you will, exercises military force to legitimize the drug trade around the world.
Clearly, drug use is considered acceptable by a large proportion of the world's population, since in spite of vast sums spent by governments in efforts to stop the drug trade, illegal drugs are widely available and easy to obtain.
The main factor that cuts against such a scenario is the technological dominance of the US military. At the moment, the hypothetical "Axis of Suppliers" would not be capable of gaining access to certain weapons such as stealth bombers and aircraft carrier task groups. Should the USA decline, however, this scenario could very well come about.
The time frame for any decline in US power is a long one, however. It took some 500 years for Rome to collapse once it transitioned from republic to empire. A wild card would be access by the cartels to nuclear devices. Needless to say, nuclear blackmail would change the equation radically.