Many lords and knights virtually bankrupted themselves, mortgaged their lands and castles and racked up enormous debt to finance their involvement in the First Crusade (Tyerson, God's War)

The Peasants Crusade, which was an unintended populist response to Urban II's sermon at Clermont, just kind of... went. It was more like a highly mobile riot than any semblance of a militarised force and essentially looted what it needed as it went across Europe, until it was policed by a Byzantine army, causing a massive diplmomatic headache for the actual Crusade when it turned up.