 He then studied in Jerusalem under Marie-Joseph Lagrange, O.P., but returned to France in 1905 for military service.On 4 August 1907, Tisserant was ordained a priest by Charles-François Turinaz, Bishop of Nancy.Tisserant served as a professor at the Pontifical Roman Athenaeum S. Apollinare and curator at the Vatican Library from 1908 to 1914, at which time he became an intelligence officer in the French Army during World War I.