After retirement, Fuller served as a reporter during the Italian invasion of Ethiopia (1935) and the Spanish Civil War (1936–1939). On his retirement in 1933, impatient with what he considered the inability of democracy to adopt military reforms, Fuller became involved with Sir Oswald Mosley and the British fascist movement. As a member of the British Union of Fascists he sat on the party's Policy Directorate and was considered one of Mosley's closest allies. He was also a member of the clandestine far-right group the Nordic League.