According to historians although the Crusades failed to drive the Muslims from Jerusalem or Byzantium, which was the initial purpose, they had major effects on the European civilisation. We can identify social, cultural, economic and scientific effects.
<em>1) The Crusades may have extended the Church authority, but they also caused social problems and upheavals.</em>
<em>2) Through the Crusades, European and Middle Eastern cultures affected eachother. The European civilisation met new types of goods, furniture etc.</em>
<em>3) Europeans improved in trade and exploration.</em>
<em>4) Scientific knowledge from the Middle East was adopted and brought back to Europe.</em>
In these ways the Crusades actually formed a basis for the coming Renaissance.