As an under age youth and listing his profession as bookbinder, Reginald Nankivell enlisted with the New Zealand Expeditionary Force on 31 May 1916. He served in England (1916–1919) on the staff of No. 1 New Zealand Hospital General Hospital, Brockenhurst, Hampshire (part of his collection of photos was taken here) and at the New Zealand Command Depot, Codford, Wiltshire. On an extended period of leave in England, from October 1917 to May 1918, he began to pursue his growing antiquarian interests. Around 1918 he started to style himself Rex de Charembac Nan Kivell.