Mezue ahịrịokwu na-esonụ: Grasett bụ nwa nwoke nke atọ nke Reverend Henry James Grasett, onye isi nke St. James Cathedral na Toronto, na Sarah Maria Stewart. Ọ gụrụ akwụkwọ n'ụlọ akwụkwọ onwe onye dị na Toronto na Leamington College maka ụmụ nwoke na England. Mgbe ọ dị afọ 19, ọ laghachiri Canada ma sonye n'òtù ndị agha Canada. Ọ lụrụ ọgụ na Niagara Peninsula n'oge
Fenian Raid nke 1866 na 2nd Battalion, Volunteer Militia Rifles nke Toronto, N'afọ 1867, ọ sonyeere ndị agha Britain na-eje ozi na Royal Canadian Regiment na Canada na England wee bulie ọkwa lieutenant n'oge ọ lara ezumike nká na Toronto na 1875, ebe ọ ghọrọ onye mmekọ na ụlọ ọrụ nke mbupu na ndị ahịa ọrụ. N'afọ 1885, e nyere ya ọkwa nke lieutenant colonel n'ime ndị agha ahụ ma tinye ya n'ọchịchị nke 10th Battalion Royal Grenadiers nke lụrụ ọgụ n'ọtụtụ agha n'oge Nnupụisi North-West nke 1885.