What does truman mean when he claims," should we fail to aid greece and turkey in this fateful hour, the effect will be far reaching to the west as well as to the east"?

By the given statement in question, Truman wanted to imply that the effect of communism was growing and if it could not be checked by aiding such countries as Greece and Turkey, then it would have far reaching effects. Truman feared that communism would slowly grip these countries in financial trouble and spread to the Latin American countries and the countries in the East at a very fast rate. 

African americans at the time just came out of slavery and needed money to provide for there families. so they joined for the money mainly.

Tenochtitlán was the capital of the aztec empire. it was a busy and bustling city where“there are daily more than 60,000 souls, buying and selling, and where are found all the kinds of merchandise produced in these countries.” when cortes arrived in 1519, theenormity of the trading market and the smoothness of it’s running both surprised and  impressed him.