Examples include the 13th century Albigensian Crusade and the Northern Crusades. Numerous massacres of Jews occurred throughout Europe during the Christian Crusades. In 1199 Pope Innocent III began the practice of proclaiming political crusades against Christian heretics. The massacres during the crusades strengthened Jewry from within spiritually. Other wars led to the Northern Crusades. Chivalry and religion were mutually influenced during the period of the Crusades. The group Muslims Against Crusades abandoned a planned protest. Trade continued nonetheless and despite papal restrictions on trade with the Muslims during the Crusades. Many Old Prussians emigrated due to Teutonic crusades. He was the first Muslim commander against the crusades. This typifies the classic knightly sword that developed during the age of the Crusades. These campaigns were subsequently given the name crusades. The focus was radically influenced by fortification and siege technologies developed during the Crusades. The fall of Acre signaled the end of the Jerusalem crusades. Angel Stadium has been the site of annual Christian Harvest Crusades since 1990.