The Children's Crusade is supposed to have involved between 15,000 and 30,000 French children, who attempted to reach the Christian Holy Land by foot and boat in an effort to reclaim Jerusalem for their faith. Historical evidence for the Crusade is dubious at best, and it is unclear whether it ever really happened.
The Children's Crusade is said to have taken place in 1212, after the Fourth Crusade, which occurred from 1202-1204. It was allegedly led by Stephen of Cloyes, a 12-year-old shepherd boy who claimed to possess a letter written by Jesus Christ himself.
This letter, he told King Philip of France in May of 1212, were orders from the Son of God for a new crusade to be organized. After the King sent the boy away, Stephen turned to his young peers, preaching around France in order to gain their support.
Making their way south through France, the many thousands of children, all of whom were said to be younger than age 12, reached the Mediterranean Sea and boarded seven boats in Marseilles.
This is where the story ends, except for the account of a priest who had traveled in North Africa. According to him, two of the boats sank and the other five were captured by pirates who sold the valuable white-skinned children into slavery.
A similar, albeit less well-known "Children's Crusade" set off from Germany in the same year. Led by a boy called Nicholas, it is said to have involved 20,000 children, unmarried women and religious men who got as far as Rome before the Pope persuaded them to go home. Only a few are said to have boarded a boat for the Holy Land.