There, he took courses via correspondence at the University of London and graduated with a degree in Ancient History in 1943. Ehrenberg enlisted in the British Army in 1943. He spent his time in the Army in the Intelligence Corps and the East Surrey Regiment, serving with the Eighth Army in Italy from 1944 to 1946 and reaching the rank of sergeant. During this period, Ehrenberg anglicised his name to Geoffrey Rudolph Elton. After his discharge from the army, Elton studied early modern history at University College London, graduating with a PhD in 1949.