From the start of Christian rule in Europe, Jews were increasingly discriminated against, at times rising to outright persecution. This sometimes took the form of events like the Rhineland massacres, and the Blood libel was often the source (falsely claiming Jews ritually murdered Christian children). Jews were also expelled from a number of countries, including from England and later Spain. In the latter case, if converted they could remain. However, as most did so only under duress, Judaism continued to be practiced in secret by many. As a result, the Spanish Inquisition was formed to root them out, along with the secret Muslims there. In the First Crusade, after the Siege of Jerusalem, all Jews and Muslims within the city were massacred by the Crusaders.