What was the outcome of the third war and how did they know Their would be no fourth

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).

the speech convinced americans that the ussr was an enemy, rather than an ally, which led to the creation of the truman doctrine.