 Eugenio Maria Giuseppe Giovanni Pacelli was born on 2 March 1876 in Rome into a family of intense Catholic piety with a history of ties to the papacy ( the " Black Nobility " ) . His parents were Filippo Pacelli ( 1837 – 1916 ) and Virginia ( née Graziosi ) Pacelli ( 1844 – 1920 ) . His grandfather , Marcantonio Pacelli , had been Under @-@ Secretary in the Papal Ministry of Finances and then Secretary of the Interior under Pope Pius IX from 1851 to 1870 and helped found the Vatican 's newspaper , L 'Osservatore Romano in 1861 . His cousin , Ernesto Pacelli , was a key financial advisor to Pope Leo XIII ; his father , Filippo Pacelli , a Franciscan tertiary , was the dean of the Roman Rota ; and his brother , Francesco Pacelli , became a lay canon lawyer and the legal advisor to Pope Pius XI , in which role he negotiated the Lateran Treaty in 1929 , the pact with Benito Mussolini , bringing an end to the Roman Question . 
