Cowper then undertook an arts degree at Sydney University finishing in 1917. He then joined the army in 1918 after having been rejected three times earlier due to an enlarged heart due to a bout of rheumatic fever.
After completing his arts degree at Sydney University in 1917, Cowper enlisted in the army in 1918. This decision came following multiple rejections in 1917 because of an enlarged heart resulting from rheumatic fever.