He was born on 29 July 1886 to Mary Ashley (died 16 Nov 1942, aged 82), who moved from Shropshire in 1898, and Ceasar (Caesar) Henry Roose (died 29 July 1925, aged 77), who moved from Germany in the 1880s, Their eldest son, Caesar junior, helped on the 67 acres Tuoro Island (in the Waikato River) family farm until he lost an appeal against military service and had to go to Trentham and Featherston military camps in 1918.