Returning to England the next year, Cary sought a post with an Irish agricultural cooperative scheme, but the project fell through. Dissatisfied and believing that he lacked the education that would provide him with a good position in the United Kingdom, Cary joined the Nigerian political service. During the First World War, he served with a Nigerian regiment fighting in the German colony of Kamerun. The short story "Umaru" (1921) describes an incident from this period in which a British officer recognises the common humanity that connects him with his African sergeant.