The Crusades were a series of events that involved the decision of who rules Jerusalem the Holy land for Christianity, Islam and Judaism. Muslims took over Jerusalem and kicked out the Christians and Jews who lived there. They also wanted to attack Constantinople the place where the Greek orthodox church was located. The king of Constantinople asked the Pope of the Roman Catholic church for men to help defend his Kingdom. The Pope announced that anyone who goes and fights will be forgiven by the gods and will get a ticket to heaven. Because of this so many peasants joined to fight against the Muslims. This was just the first crusade. Their were 8 Crusades in all. At the end of the Crusades nothing really changed. It went back to the way it was. Muslims ruled and nothing changed. But it did affect Europe in a good way. It improved the trading system and it gave Kings more power. Most of the Knights, Lords and Peasants died so the king claimed all the land. It was like a fresh start for the king and That's a short summary on the Crusades.
The Black Death or plague was a disease that originated from flees. Scientists believed that the flees gave the disease to rats and the rats brought it to Europe. The disease started in China and was brought to Europe when ships from China deported with trades. The disease quickly spread and killed more than 1/3 of Europe. When a person gets The Black Death they get covered with black spots that look like pimples but bigger and filled with puss. It lasted so long because people didn't take as many baths as they do now. Another reason is m=because they didn't yet discover a cure and since it was spreading so fast they didn't have that much time either. No one knows exactly how the Black Plague ended, some believe that a different type of rat who was immune to the disease cam in and some believe that people started washing up more often and the disease was sopped that way. Now days we know the disease was caused by the Bubonic Plague. Now the disease is really rare but if you do get it you will most likely not die cause there is a CURE!