• Occurred between late 11th and late 13th centuries
• United groups of European kingdoms against common enemy
• Composed of upper and lower class people
• Motivations varied: political, religious, monetary, other
• Usually organized by the Pope or desired permission from them
  • Pope Urban II organized the first crusade
• Had an explicit religious orientation
• Were hugely expensive and required fundraising
• Often failed or were curtailed because of logistic problems
• Did not leave immediately, set up crusader states
  • Had markets in which Italian city states traded in