I am not sure which Encyclical you are referring to but, Pope's Greg XVI & Pius IX both forced to take loans from Rothschild. This is because the banker threatened to throw out of the European cartel anyone else who would loan money to Vatican-- so no one else would.
It should be noted that when the Pope discovers the Alta Vendita, he determines that the same people who loaned him money are the same who have robbed him of Papal States during Italian Revolution-- The loans are not repaid.
See J Pollard-- Money & Modern Papacy.