In 1916 he went straight from school into the army, at first in the Royal Artillery, then in 1917 he was commissioned as second lieutenant in the Gloucestershire Regiment.
After graduating he studied theology at Westcott House, Cambridge, and was ordained in the Church of England.
He was also the Scoutmaster of St Paul's College in Hong Kong and was enthusiastic in Scouting activities.
From 1936 to 1946 – throughout the Second Sino-Japanese War and World War II – he was based in Canton (now Guangzhou) in southern China as a missionary for the Church Missionary Society, but continued as Hong Kong Colony Commissioner for Boy Scouts despite the Japanese occupation of Hong Kong.
Halward appointed Chinese district commissioners and they significantly helped to develop Scouting in Hong Kong.