Source: 18th Battalion Nominal Roll, April 1915.
Find-A-Grave
Family Search: When Dennis Henry Rayner was born on 31 October 1894, in Halstead, Essex, England, United Kingdom, his father, Charles Henry Rayner, was 28 and his mother, Fanny, was 25. He immigrated to Canada in 1910. He registered for military service in 1914. In 1914, at the age of 20, his occupation is listed as labourer. He died in 1975, in Essex, England, United Kingdom, at the age of 81.
May have joined under aged as birth records indicate he was born 1894.
War Diary of the 18th Battalion CEF 