Grasett aiva mwanakomana wechitatu waReverend Henry James Grasett, Rector weSt. James Cathedral muToronto, naSarah Maria Stewart. Akadzidza pachikoro chepachivande muToronto uye paLeamington College yeVakomana muEngland. Pazera ramakore 19, akadzokera kuCanada ndokupinda muchiuto cheCanada. Akarwa paNiagara Peninsula panguva yechiuto cheFenian
Muna 1867, akabatana neBritish Army achishanda neThe Royal Canadian Regiment muCanada neEngland uye akasimuka kusvika pachinzvimbo chemutevedzeri panguva yaakasiya basa kuToronto muna 1875, kwaakazova mudiwa mune imwe kambani yekutumira uye vatengesi vekomisheni. Muna 1885, akapiwa chinzvimbo chemutevedzeri wemukuru wemauto uye akaiswa mukutungamira kwe10th Battalion Royal Grenadiers iyo yakarwa muhondo dzinoverengeka panguva yeNorth-West Rebellion ya1885.