Christian knights and peasants from across Western Europe launched the Crusades (Holy Wars) to recapture the Holy Land from Muslim control. They slaughtered all non-Christians in their path, not just in the Holy Land but throughout Europe as well. Crusade military units such as the Knights Templar, Teutonic Knights, and Hospitallers built impressive castles, fortresses, and tunnels in Acre and the Galilee to protect pilgrims traveling to and from the Holy Land.