The objectives of the Crusades were to check the spread of Islam, to retake control of the Holy Land, to conquer pagan areas, and to recapture formerly Christian territories. The Crusades were seen by many of their participants as a means of redemption and expiation for sins.
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The vulnerabilities and challenges that more complex civilizations faced disease, conflict, and shortages of food since these societies were so populated. Due to its sheer population, an epidemic could happen if an outbreak of disease happens.
However, countermeasures were prepared to address these vulnerabilities, such as storing food and water.
The debate during the Gilded Age was between "free-traders" and "protectionists". Generally, people in agriculture prefferred lower tariffs, because it enabled them to more easily export their agricultural products, which there was a surplus of in the US, and provided competition for industrial products, which would keep prices low.
For the opposite reason, people in more industrial areas of the country wanted higher tariffs, or a more protectionist policy, so that the manufacturing sector could continue to develop, and they wouldn't have to compete with foreign manufactured goods.