Crusade in Jeans (1973) is a children's book written by Thea Beckman . It contains a fictional account of the children's crusade of 1212, as witnessed by Rudolph Wega, a boy from the 20th century. The original Dutch title is Kruistocht in spijkerbroek.

Currently a film of the book is in production.

Plot

Rudolph Wega is a fourteen year-old who volunteers for an experiment with a time machine. The experiment goes well, but through an accident Rudolph is stranded in the 13th century. He joins the children's crusade, and through his modern-day knowledge, he manages to save a lot of children from horrible fates. However, his knowledge also leads to accusations of witchcraft.