[1][3] After the war, he pursued a degree in law at the École Nationale des Chartes and was appointed a member of the French Academy in Rome in 1923.
[1][3] Grat spent two years researching Latin texts in the Vatican and discovered several previously unknown works written by Tacitus.
[1][2] After returning to France in 1925, he became a lecturer at the École pratique des hautes études and was appointed a professor of palaeography at Sorbonne University.
[1][3] Sitting in the Assembly with members of the conservative Republican Federation party, he was concerned with agriculture, labor policies, and foreign affairs.
[1][3] During the Second World War, Grat re-enlisted in the army and served on the frontline, again being rewarded the Croix de Guerre for his service.