Conversation so far:
what was Bernard Lewis's academic career like?
In 1936, Bernard Lewis graduated from the School of Oriental Studies at the University of London with a BA in history with special reference to the Near and Middle East.
what did Bernard Lewis do after he graduated?
Bernard Lewis earned his PhD three years later, also from SOAS.
what was Bernard Lewis's job after graduating with the PHD
During the Second World War, Bernard Lewis served in the British Army.
Are there any other interesting aspects about Bernard Lewis?
Bernard Lewis served in the British Army in the Royal Armoured Corps and as a Corporal in the Intelligence Corps in 1940–41 before being seconded to the Foreign Office.
why was Bernard Lewis seconded to the foreign office?

Question: what was his greatest accomplishment?
Self-contained rewrite: what was Bernard Lewis's greatest accomplishment?