The Canadian Great War Project is the largest fully searchable database dedicated to the Canadian men and women that served in the Canadian Expeditionary Force (CEF) during the Great War (1914-1919).
The records available for viewing and downloading are quite remarkable. Using the search function I entered Mahon. In seconds entire records of Mahons who registered in the Great War were listed. The first one was a Thomas Mahon. Downloading his collection that consists of 52 pages I discovered this was Thomas James Henry Mahon; son of Richard Peter Mahon and Mary Smith; son of James Mahon and Mary Boshart; son of James Mahon and Ellen Troy.
In 1918 Thomas James Henry Mahon enlisted in the great war. He survived. Below is his Recruitment record.
The collection consists of his initial recruitment records, dental records, health records (including the lab report of his urine sample while in hospital with pneumonia), payroll and pension records, and so on. Another interesting fact that his mother was listed as “Maggie” Mahon and not Mary. This may help researchers who receive no hits on Mary Mahon.
If you are interested in this invaluable resource look up Canadian Great War Project hosted by the University of Victoria. You won't regret it.