Some historians indicate the Children's Crusades (1212) of Stephen and Nicolas mark the end of the effectiveness of the Crusades. The Pope would not bless these crusades, neither would he stop them. The speculation is that the Pope hoped the children would shame the kingdoms and empires of Europe into mounting another proper crusade as money and enthusiasm were waning. Another deterrent to effectiveness was the fall of Acre in 1291. It was the last Christian city to fall.