Robin Hanson reminds us that hindsight bias can make familiar outcomes seem inevitable, even if those outcomes were not at all certain before the fact. For instance, the South had a 42% chance of winning the war:
Historians have long wondered whether the Southern Confederacy had a realistic chance at winning the American Civil War. We provide some quantitative evidence on this question by introducing a new methodology for estimating the probability of winning a civil war or revolution based on decisions in financial markets. Using a unique dataset of Confederate gold bonds in Amsterdam, we apply this methodology to estimate the probability of a Southern victory from the summer of 1863 until the end of the war. Our results suggest that European investors gave the Confederacy approximately a 42 percent chance of victory prior to the battle of Gettysburg/Vicksburg. News of the severity of the two rebel defeats led to a sell-off in Confederate bonds. By the end of 1863, the probability of a Southern victory fell to about 15 percent. Confederate victory prospects generally decreased for the remainder of the war.