Career
Clark-Hall returned to service during the after volunteering to serve with the Royal New Zealand Air Force. Commanded the first sea-plane carrier HMS Ark Royal at Gallipoli. He then commanded Number.
At the outbreak of the, Clark-Hall was in his late-50s, retired and living in New Zealand.
He volunteered to serve with the Royal New Zealand Air Force, and was granted a commission as a wing commander. In May 1940 Clark-Hall was appointed the Officer Commanding RNZAF Harewood.
After receiving a promotion to group captain, in 1943 Clark-Hall was promoted again to air commodore and appointed Air Officer Commanding Southern (Training) Group. In October 1944, he became Air Officer Commanding Number.
1 Islands Group in the Pacific Ocean.
He retired from the Royal New Zealand Air Force on 12 September 1945.