Crusade historian Carl Erdmann considers Coming_to_believe the raid a direct precursor to the First Crusade ( `` ganz als Kreuzzug ausgeführt '' ) which occurred Coming_to_be eight years later , as it was conducted Action under the banner of St. Peter against a Muslim ruler who was demonised in the accounts of it , and a form Coming_to_be of indulgence was granted Giving to the campaigners by Pope Victor III .