What was one of the main causes of the American Civil War?

A common explanation is that the Civil War was fought over the moral issue of slavery. In fact, it was the economics of slavery and political control of that system that was central to the conflict. A key issue was states' rights.

the conditions that made the byzantine empire vulnerable to attacks by the muslin turks were the sack of constantinople by western crusaders, the conquests of the sultanate of rum, presence of rival kingdoms and finally the set up of fiefdoms at the empire which were owned by the ghazis (turkish warriors).