The success of the South relied absolutely on recognition by Britain; and Britain refused to supply it because of the pro-slavery stance taken by the confederacy. In fact the failure of the South worked to Britain's favour- it managed to establish cotton farms in labour cheap parts of the Empire and in Egypt as well as weakening France in its misguided pursuit of a Mexican crown. workers in the cotton mills in the north of England sent letters of support to Lincoln and even contributed money to the Northern war effort while their mills stood idle for want of Southern cotton. Liverpool dock workers refused to unload much of the cotton that was smuggled out of the South. Britain put principle above interest in this matter.
the Southern seccession was very obviously a ploy to overthrow the government of the US by making Lincoln's presidency untenable and returning to the Union under its own terms.