The Children’s Crusade of 1212, led by 12-year-old Stephen of Cloyes, was approved by neither King Philip nor the Pope, but that didn’t stop Stephen and his army of children (which, according to legend, was as large as 30,000 people). Another similar group of child crusaders formed in Germany, led by Nicholas of Cologne. They supposedly carried crosses and banners instead of weapons and optimistically believed they could convert people through their words and divine intervention. As OP mentioned, the Crusaders hit a wall, so to speak, around the time they made it to Genoa, Italy, as many grew tired, hungry, and did not speak the language. The groups fell apart when they hit the coastal cities, where they were supposed to wait for boats to the Holy Land. You can read about them more in-depth here.