How did windmills impact the frontier? A. They provided a steady supply of water for crops.
B. They served as a source of light in West Texas,
C. They caused the open frontier to close.
D. They increased the cost of electricity

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).

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chamberlains goal was to stop the uk ad germany from fighting which he went to hitler and asked if he could sign a peace treaty between germany and the uk