Opportunity cost refers to what you have to give up to buy what you want in terms of other goods or services. When economists use the word “cost,” we usually mean opportunity cost.
The Crusades were initiated by the Catholic Church in order to gain control of Jerusalem again, as it has fallen into the hands of the Muslims. While the Catholic Church had its goals in conquering Jerusalem, including wealth and power, it didn't foresee that the organizing of the Crusades its going to actually backfire on it and make the biggest blow to it.
The Crusades themselves had mixed outcome, sometimes winning, sometimes losing. What had much greater effect was that the Crusaders managed to bring in Europe lot of things from Asia which turned out to change the course of the history.
Because the Crusaders were in constant contact with the Muslims, they brought in numerous technological advancement in Europe. Also, through them, some of the ancient literature from Greece and Rome came back to Europe.
This prompted a huge interest among the people, especially the ones higher in the hierarchy, as they saw the potential of the new technology, but also the potential for the future based on the ancient literature. The end result was technological boom in Europe, loss of power by the Catholic Church, the Age of Discoveries, or all put in one, the Renaissance.
It should be active in promoting the social and economic welfare of citizens
Many native Americans were forced into labor on roads
