Using a unique dataset of Confederate gold bonds in Amsterdam, we... 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.
--Marc Weidenmeir and Kim Oosterlinck, "Victory or Repudiation? The Probability of the Southern Confederacy Winning the Civil War"