The American South in 1861 thought that it was the swing producer of a key industrial commodity and through this economic bottleneck it could squeeze foreign support and recognition in its rebellion against the North. Cotton diplomacy and the belief that major power economies would fail if cotton was withheld or made too expensive was one of the impetuous for the Southern belief that they only needed to be able to fight a short war as that was the only war that they had a chance of winning.
Instead the combination of large strategic cotton reserves from the bumper crop of 1860, European fear of a general war with the Federal United States (probably due to still fresh memories of US successes as commerce raiders in 1812 as well as a potential fracturing of the Concert of Vienna), and fairly rapid substitution of cotton supplies from Mexico, Egypt and India dramatically reduced the value and credibility of Confederate cotton diplomacy.
In my post on Bolivian natural gas rent seeking a couple of days ago, I had pointed out a few other examples of local sub-national groups seeking to use at least the perception of a key commodity bottleneck to overleverage their bids for greater de facto or de jure autonomy in southern Iraq and Nigeria. The Sunni Arab insurgencies pounding of the northern Kirkuk-Ceyhan pipeline system has been a counterbid to reduce the leverage of Iraqi Kurds to do the same thing.
I am speculating, and would love to be corrected, if bottleneck intensification and rent seeking behavior is more common at the dawn of change in economic systems as the bottlenecks that can be manipulated to apply the most pressure on major power economies are narrowest when they have become the most exploited and that substitution is near, but not quite available just yet.
The US Civil War was at the dawn of the transition from internal water power to coal and steam power and now we seem to be at a transitional stage where the marginal increases in energy expenditures are electrical and non-petroleum derived. Yet we are still at least a few years off from this change-over and the value of the chokepoint commodity is very high and anyone with more than three wells can credibly claim to be a swing producer at this time....