In 1835, he was appointed the second High Constable of Toronto, however, he was the first to not also be the city's only constable. During his tenure, in 1835, the Toronto Police Department was first organized when the city retained five full-time constables, the first organized police force in Canada. Kingsmill was a member of the Orange Order and he recruited his constables from the Order's ranks, a practice later found by a provincial commission of inquiry to have led the police to take a highly sectarian character. This was a period of sectarian conflict in Toronto between the Protestant majority and the largely Irish Catholic minority and the police often supported their fellow Orangemen during anti-Catholic rioting. During the Upper Canada Rebellion of 1837, Kingsmill aided the Lieutenant Governor of Upper Canada, Sir Francis Bond Head, in putting down the uprising. and in the years following the 1837 Rebellion also were used by incumbent Tory politicians to break up meetings of Reformers.