Well crusades always work out great. Let’s read about a famous one!

A boy began to preach in either France or Germany, claiming that he had been visited by Jesus, who instructed him to lead a crusade in order to peacefully convert Muslims to Christianity. Through a series of portents and miracles, he gained a following of up to 30,000 children. He led his followers south towards the Mediterranean Sea, in the belief that the sea would part on their arrival, which would allow him and his followers to walk to Jerusalem. This did not happen. Instead, two French merchants promised to take some children across the sea to the Holy Land. However, the children were either taken to Tunisia where they were sold into slavery by the merchants, or shipwrecked on San Pietro Island off Sardinia.