Career
When World War I began, Hallonquist was chief clerk of a bank in British Columbia. He joined the 19th Reserve Battalion of the Canadian Expeditionary Force, only to transfer to the Royal Flying Corps. He trained with 26 and 73 Squadrons before being posted on 23 January 1918 to 28 Squadron in Italy as an Honorary Captain.
He opened his victory roll on 17 April 1918.
On 29 October 1918, Hallonquist was shot down by anti-aircraft fire. He spent a short period as a prisoner of war before returning to Canada.