The Crusades had a tremendous impact in the political, economic and social structures in Europe. Some of the many impacts were that it brought up the age of exploration, it led to the renaissance, it helped in the decline of feudalism, and it helped the rise of the middle class.
The political system had a big change after the Crusades in Europe. The feudal system was weakened as a result of the Crusades because when the large land owners died, the land didn't have a land owner. Another reason was because they went into debt to pay for the Crusade or for ransom. Since there was no victory, there was no loot to pay back. They lost their fiefs to merchants and bankers who provided loans. When the feudal system went down, the monarchy went up and kings became more powerful.
The Crusades had impacted the economic system in Europe dramatically. Trade is huge in Europe and all around the world as well. Trade is the most important thing in life today. The age of exploration came because the Crusades introduced new foods and items from the Orient such as silks and spices, and the Muslims who they tried to trade with to get these items were enemies, it was difficult and also not worth it. The Middle man was taking too much profit, so they tried to seek a direct route to Asia. To do this, they first tried to go around Africa. They did manage to go to India. Then, they tried to go the other way around the world instead. When they sailed across the Atlantic to Asia, they had badly miscalculated the size of the earth and therefore ran into North America. This is how America was discovered.
The Crusades also led to the Renaissance. The Islamic world preserved the knowledge of Greece, science, architecture, philosophy, medicine, and art. They also built upon this making it better. Their medical system was excellent for the time. They had hospitals, medical schools, anesthesia, and mobile clinics. Their mathematics also excelled. They had Arabic numerals, algebra, zero, and negative numbers. One last thing that was very good in the Islamic world was that the astronomy and navigation were very accurate. They measured the size of the earth, invented the magnetic compass, and invented the astrolabe.
In the social structure, the middle class rose because traders, merchants, artisans in towns benefited from new products from the East. Peasants left the manor and died on crusades, returned but not to the manor, or moved to towns for paying work. The Black plague also decreased the population by up to 1/3 lack of labor, lack of heirs.
The Crusades brought many changes, most of the changes that are still used today. Trade between countries is now one of the most important aspects in today's life. People in towns still have rights, and some countries still have kings. The middle class has become the biggest class. The crusades helped make the modern world what we know it as.