What nazi action marked the final stage of the “final solution”?

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).

a element i know of that abused the power was the taxes the taxes were very heavy due to the war.