In 1863, Abraham Lincoln’s reputation in Europe was failing. Much of the Europe saw him as a tyrant who ignored the rule of law, imprisoned political enemies, and turned a blind eye toward war crimes by his generals against the Southern rebels. That’s not saying that they supported the Confederacy. They were viewed as backwards, fighting to preserve antiquated slavery. The American Civil War was seen as an internal issue, of little concern for Europeans, and the North was winning. Everyone expected the United States to survive as a Republic, albeit with some changes. But then General Sherman started marching south. News of pillaging and burning of civilian homes, as well as rumors of executions and rape made it back to Europe. General Sherman gained a reputation similar to Attila the Hun or Genghis Kahn. The Confederate separatists were viewed as freedom fighters, not unlike the Colonials that won independence from England. All but the most adamant slavery opponents were won over to at least vocal support of the Confederate cause. Both the French and the English saw opportunity in this, and began to get involved. By supporting the Southern rebellion, they could weaken their new imperial rival with the support of many of their citizens.
England and France joined forces to attack United States cities from the sea.