William Brooks, the son of a seaman in the Merchant Navy, was born in London in 1898. After leaving school he worked at the Woolwich Aresnal where he was apprentices as an iron and steel moulder.
After coming under pressure from members of the Order of the White Feather, Brooks joined the British Army in 1915. A member of the Royal Engineers, Brooks was sent to France in January, 1917, to help build a broad-gauge railway.